Complex Pathways Towards Emergent Pastoral Settlements: New Research on the Bronze Age Xindian Culture of Northwest China

The turn of the third to second millennia BC (i.e., c. 4000 BP) is a time when the western regions of the area currently within the People’s Republic of China witnessed a number of radical changes in patterns of subsistence, organization of communities and general ways of life (see Womack et al., 2017; Yang et al., 2019a, 2019b). A network of ‘proto-Silk Roads’ that began to emerge in the preceding millennium involved trade, exchange, and population movements and resulted in the gradual introduction of new technologies—including metallurgy and West Asian or Central Asian domesticates, such as wheat, barley, caprines, cattle and eventually horses—alongside the movement of ancient people (recent studies and summaries of these processes can be found in: Brunson et al., 2020; d’Alpoim Guedes & Bocinsky, 2018; Dong et al., 2017; Flad, 2017; Han, 2012; Jaang, 2015; Jaffe & Flad, 2018; Leipe et al., 2019; Lin, 2016; Lister et al., 2018; Liu et al., 2017; Long et al., 2018; Mei et al., 2015; Ventresca Miller & Makarewicz, 2019; Womack et al., 2021, among others). An apparent confluence of social and cultural developments coupled with the onset of cooler and drier conditions, sometimes termed the ‘ ~ 4.2 k BP event’, has led scholars to assign a pivotal role to the effects of climate change on these processes across this broad region (e.g. An et al., 2005; Liu & Feng, 2012; Wu & Liu, 2004; and see Jaffe et al., 2020).

On the macroscale, there is considerable evidence that climate change corresponded to significant changes in human behavior. On the Tibetan plateau, for example, computational climatic models show that related climate changes may have led to a major transition in subsistence regimes that resulted in a shift from millet farming to more cold-adapted crops like barley (d’Alpoim Guedes, 2016; d’Alpoim Guedes et al., 2013, 2015). Climate change does not impact all regions of the globe in a homogeneous fashion, and the integration of environmental and archaeological studies can provide data about not only the types of challenges that people faced but how they reacted to these in specific local contexts (Contreras, 2016; d’Alpoim Guedes et al., 2016a, 2016b; Hudson et al., 2012; Haldon et al., 2018; Kintigh et al., 2014). In lower altitude regions of the loess plateau off the Tibetan plateau it is unclear what impacts, if any, environmental change had on subsistence and society, due to a lack of data on human practices and organization from excavated settlements (Jaffe & Hein, 2020).

One proposed set of changes is a possible shift to increasingly pastoralist subsistence practices, a process that relates to the important issue of emergent pastoralism in many global contexts (Frachetti, 2012; Harris, 1996; Honeychurch & Makarewicz, 2016; Marshall et al., 2018; Spengler & Mueller, 2019). In what today constitutes the western loess plateau and Tao river valley, some scholars propose a large-scale and speedy transition from mostly sedentary agricultural economies to mobile pastoral subsistence systems (e.g. Dong et al., 2013; Liu and Feng, 2012; Wagner et al, 2013; Wu & Liu, 2004). To date, however, there is relatively sparse residential, archaeobotanical and zooarchaeological data on how people adapted their cultural and subsistence practices in specific regions within the wide area of northern China (Jaffe & Hein, 2020). In this paper, we provide new data from two residential settlements dating to the cultural phase after a transition attributed, at least in part, to environmental change. We argue that rather than changing their subsistence practices completely, people maintained elements of earlier cultivation and animal foddering systems, selectively incorporating new plants and animals into their repertoire. These results fit a pattern observed in other contexts of locally-specific strategies that incorporate pastoral and agrarian practices in ways that are appropriate to specific changing environmental and socio-political conditions (e.g. Brunson et al., 2016; Hermes et al., 2019; Spengler et al., 2014; Ventresca Miller & Makarewicz, 2019; Ventresca Miller et al., 2020).

The developing proto-Silk Road networks loosely tied together communities that were widely spread across different environments: from the arid deserts of the Gobi and nearby parts of the Hexi Corridor, to the more arable river-valleys of parts of Gansu and Qinghai, where successors to those who created the painted pottery traditions of the Majiayao 马家窑 (c. 3300–2650 BC/5250–4600 BP), Banshan 半山 (c. 2800–2300 BC/4750–4250 BP) and Machang 马厂 (c. 2300–1950 BC/4250–3900 BP) archaeological cultures of the third millennium BC lived in settlements associated with the Qijia culture 齐家 (c. 2200–1500 BC/4150–3450 BP) (see Table 1 with associated dates). The widespread Qijia culture was characterized by agricultural communities who adopted new technologies and set the stage for an increasingly interconnected world in Bronze Age North China (see Dong et al., 2017; Jaang, 2015; Jaffe & Flad, 2018; Lin, 2016; Womack et al., 2017, 2019a). Qijia cultural influence was widespread, but it is the next chronological stage when the development of a variety of social practices and cultural components is seen to have contributed to the increasingly complex origin of Chinese civilization.

This next chronological phase (i.e., post-1500 BC/3450 BP) has, indeed, increasingly been the focus of intensified examination in regions to the east of the core area of Qijia development. For example, the Central Plains development—from the Erlitou culture (c. 1750–1500 BC/3700–3450 BP) to subsequent stages of the Bronze Age associated with the period of the Shang Dynasty—has been a consistent focus of archaeological interest centered on studies of early state development in China (Bagley, 1999; Campbell, 2014; Fitzgerald-Huber, 1995; Liu & Chen, 2012; Liu & Xu, 2007; Xu, 2009), and on the emergence of a more globalized world of polities in the early first millennium BC (Shelach & Jaffe, 2014). However, in the core regions of the Qijia culture itself, mostly within modern-day Gansu, far less is known about the ‘post-Qijia’ period, although a basic cultural chronology is generally accepted. Following the Qijia culture in these regions, a number of archaeological cultures sprang up during the latter part of the second and early first millennia BC (Li et al., 2010; Wang, 2012). Some cultures—including the Kayue 卡约 (c. 1800–1500 BC/3750–3450 BP) and Siba 四坝 (c. 1950–1550 BC/3900–3500 BP) cultures in the northern parts of Gansu and Qinghai—overlap with the latter part of the Qijia date range but post-date Qijia in specific regions. Others—such as the Xindian 辛店 (c. 1600–600 BC/3550–2550 BP) and Siwa 寺 洼 (c. 1300–500 BC/3250–2450 BP) cultures in the Central and Eastern parts of Gansu Province—follow the later Qijia materials that are in these regions (Shui, 2001). Their character and chronology are poorly understood—to date only a handful of sites, mostly cemeteries, have been excavated—yet they remain critical for understanding the broader universe of communities in the region around 3000 years ago (Jaffe & Hein, 2020). Siwa and Xindian, in particular, are archaeological traditions associated with communities that may have engaged in new subsistence practices, such as animal herding, following a long process of climate changes.

The study of these Siwa and Xindian archaeological cultures began with their initial definition and classification by Andersson (1925) in the early twentieth century. From that point to the present, much of the archaeological work in the associated region and time period has revolved around sporadic excavation of cemetery sites and an associated close study of ceramic styles aimed at defining archaeological cultures (Li et al., 2010; Lu, 2013; Shui, 2001; Wang, 2012). Typology and classification of these ceramics is pursued as an end in itself, as occurs in other areas of Chinese archaeology (Campbell, 2014; Hein, 2016; Jaffe et al., 2018; Shelach, 2009), with the presumption that outlining the similarities and differences in ceramics provides a direct line of evidence of social relationships among different groups. Consequently, little is known about site size and layout during these pivotal times. Even less can be said of broader economic patterns or aspects of social relations not reflected in ceramic styles, although there are some proposals based on scattered evidence, in large part framed in relation to environmental changes and their effects on subsistence practices (e.g. Dong et al., 2013).

A common view is that the end of the Qijia culture was associated with agricultural collapse and the emergence of economies reconstructed as based on pastoral, and even nomadic, sheep and goat herding—chief among them the Siwa culture (e.g. Liu et al., 2010). Such assumptions, however, are based on cursory data and represent two principal lines of evidence that require critically examination: one is the belief that a severe ~ 4.2 k BP climatic event documented in various places in the northern hemisphere would have forced a shift in subsistence practices (e.g. Li et al., 2015; Ma et al., 2014, 2016; and see Jaffe et al., 2020). A second is the identification of what appear to be deer-hunting motifs found painted on Xindian ceramic vessels. These have been interpreted as suggesting the prominence of such animals in the economy (e.g. Xie, 2002). These arguments, however, are based on assumptions that have not yet been substantiated by corresponding faunal, palaeobotanical, or other evidence allowing for inferences on subsistence practices during that period (Jaffe & Hein, 2020).

A concerted focus is needed to assess this proposed transition in climate and subsistence practices, at both the regional (e.g. Yang et al., 2019a, 2019b) and local level, considering individual sites and sub-regions carefully to understand local manifestations of social and economic change during this period. Here we report on the results of such an effort focused on the Tao River valley, where the type sites of the Qijia culture (Qijiaping), Xindian culture (Xindian) and Siwa culture (Siwashan) are located. The Tao River Archaeological Project (TRAP)—a collaborative effort between Harvard University, the Gansu Provincial Institute of Archaeology, and Beijing University—is focused on investigating various aspects of technological change and the social and economic character of the Tao River valley throughout the late Neolithic and Bronze Age periods. Recent work at both the Xindian type-site and a nearby contemporaneous site called Huizuiwa affords a new window into the internal layout of Xindian period sites, as well as a finer understanding of local-specific community economic strategies in their environmental contexts (Fig. 1). Survey and excavation of domestic sites, combined with a number of analytical studies—ceramic artifacts, botanical and zooarchaeological remains and geomorphological inspections—provide, for the first time, a picture of these communities and their lifeways. We propose the combination of these methods to be a useful approach for continued work in this region. Indeed, even as the results of our work are a culmination of several years of field and laboratory work, they are still limited. Even so, they are far beyond anything done in the region to date (and see overview below). As such, they allow us to evaluate the models that dominate the current literature. We observe that Xindian sites in the Tao River valley were more compact than residential sites of earlier periods, and they seem preferentially to be positioned defensively. Furthermore, remains of animals and plants from Xindian culture contexts at Huizuiwa reflect a considerable investment in the raising of sheep and goat, but also a continued reliance on domesticated crops, with a shift toward and increased reliance on grains introduced from western Eurasia: wheat and barley. Based on comparison with data from the Qijia period in the same region, we observe that these changes occur over a relatively long period, indicating that claims that the post-Qijia culture phases developed as an immediate and punctuated response to the aforementioned climate changes around 4.2 k BP should be questioned in the case of the communities in the Tao River valley.

The western regions of modern-day China, particularly around the headwaters of the Yellow River and surrounding regions, have not received the same level of scholarly focus as the lower Yellow River valley, traditionally viewed as the center of Chinese civilization. In fact, connections and influences between these western regions and the traditional core have shaped studies of cultural developments in both areas (Jaffe & Hein, 2020). Examples of connections and influences are purported to have been found, archaeologically, in the styles of early bronze artifacts at Erlitou (Mei et al., 2015), and in textual data on Qiang captives, possibly brought from the west, and who were scarified by the Shang in the Central Plains (Xia, 1949; Hu, 1980)—a connection proposed through stable isotope studies as well (Cheung et al., 2017). A number of scholars have viewed the upper Yellow River and adjacent areas, including the headwaters of the Wei River, as the origins of the barbarian hordes who would bring down the Western Zhou Dynasty (Zhao, 1989; Li, 2006). This is also the region in which the Qin state developed, and from which it would go on to unite ‘all under heaven’ and create the first Chinese empire (Pines et al., 2013).

When Swedish geologist turned archaeologist J. G. Andersson first worked in this region, China’s Stone Age past was not well understood (Chang, 1986, pp. 4–5). Andersson set out to investigate a hypothesis of a western origin for China’s past. His work initially led him to posit that the Yangshao Neolithic culture might have roots in migrants from Eastern Europe (Andersson, 1925). His work in Gansu was part of an effort to document potential connections between these far-flung parts of Eurasia. While ideas of direct connections across Eurasia have long been discredited and repudiated (including by Andersson himself: see Fiskesjö & Chen, 2004), his archaeological discoveries and cultural classification have had a lasting effect, most notably in establishing an initial typology and sequence for ceramic traditions and associated cultures.

Over the past few decades, archaeological work has shown that the Neolithic trajectory of development in this western region had its own character, albeit one connected to some characteristics of traditions further to the east—mostly seen through ceramic stylistic comparisons (Li et al., 2010; Wang, 2012). The widespread but somewhat heterogeneous Yangshao archaeological culture was followed by a sequence of painted pottery cultures, which are often grouped under the term ‘Majiayao culture’ (which was chronologically the first of them) (see Table 1). In sequence these successive traditions are the Majiayao, Banshan and Machang. These are followed by the Qijia culture, which was quite widely distributed, encompassing parts of the Hexi Corridor and most of southeastern Gansu, and with evident connections to places as far away as the sites of Erlitou in Henan (Fitzgerald-Huber, 1995; Jaang, 2011; Mei, 2003) and Shimao in northern Shaanxi (Yan, 2010)—although the nature of these contacts remains unclear, as they are evidenced by sporadic finds of material culture and similar stylistic decoration alone. Overlapping with and following the end of the Qijia culture, a number of cultures sprang up during the second millennium BC. Among these, was the Xindian culture (c. 1600–600 BC or c. 3550–2550 BP, see Table 1).

The Xindian culture was given its name by Andersson after the initial discovery in 1924 of a new ceramic facies at the site of Xindian, Lintao County, Gansu Province. Having discovered Xindian-type ceramics at two settlements and four grave sites in 1925, Andersson declared enthusiastically: ‘the Hsin Tien (Xindian) stage is one of the best known in the whole prehistoric record of Kansu’ (Andersson, 1925, p. 15), a statement that seems ironic in hindsight, given that the other types of material first identified by Andersson are now much better known than Xindian-type material. Conversely, the Xindian material does not appear at all in the Zhongguo Kaoguxue 中国考古学 [Chinese Archaeology] series published by the Academy of Social Sciences (Zhongguo Shehui, 2003), but Xindian culture sites are reported in the Gansu volume of the Zhongguo Wenwu Dituji 中国文物地图集 [Atlas of Cultural Heritage in China]. What still holds true, though, is Andersson’s assessment that the Xindian-type pottery differs markedly from all other ceramics in Gansu in ceramic quality as well as decorative motifs. Andersson saw this ceramic tradition as having developed from the Machang tradition, pointing to the foreshadowing of typical Xindian vessel forms in Machang assemblages (Andersson, 1943, p. 217). The date of the Xindian culture was pushed considerably later by the 1956 discovery of Zhangjiazui and Wujia, where Xindian material was found in layers above Qijia remains, showing that Xindian not only postdated Machang, but also Qijia (An, 1956).

Survey and excavation work conducted by Chinese teams since the late 1940s led to heated discussions about the nature of Xindian as an archaeological culture and its connection with other cultures, phases, or sub-groups. The Xindian culture is still believed to have derived from the Qijia culture (Nan, 1989), but after the discovery of Zhangjiazui 张家咀 and Jijiachuan 姬家川 sites in 1947, both of them yielding ceramics similar to the material found at Xindian yet having particularities of their own, scholars started distinguishing two Xindian sub-groups (Zhongguo, 1980a), adding a third with the discovery of Shanjiatou 山家头 in 1984 (Pei, 1987). The material from Tangwangchuan 唐汪川 discovered in 1956 leads to much additional controversy, with An (1956) proposing the term Tangwang-style pottery and suggesting the existence of a separate Tangwang culture.

At present, the controversy around the internal division of the Xindian material continues as different scholars distinguish different subtypes (An, 1999; Yan, 1978; Ren, 2016). A common approach is to distinguish between ceramic assemblage styles found in Zhangjiazui, Jijiachuan and Shanjiatou types. Xie (2002) finds that the Shanjiatou type, which is found in Minghe county, Qinghai along the upper regions of the Yellow river, along the Tao river, and along the Xia river, is succeeded by the Zhangjiazui type as its second phase. In contrast, the Jijiachuan type is reported as more widespread and found along the upper reaches of the Yellow river valley, along the Xia and Tao rivers and additionally as far east as the upper reaches of the Wei river and Baoji county in Shaanxi. Shui (2001) agrees with this assessment, though he finds the Jijiachuan to be an earlier variant of Xindian culture. The details of these subtypes and the related typological debates center on the forms and decorations on Xindian-style ceramics.

So far, the few existing summary publications on Xindian have focused on issues of typology based on ceramic forms and decoration, providing little information on issues of technology and describing even the occurrence of specific ceramic forms or decorations with vague terms such as ‘common’, ‘some’, or ‘few’ rather than absolute numbers or percentages (e.g. Ren, 2019; Xie, 1985). This is because the majority of Xindian sites were either excavated early (i.e. in the 1930s to 1950s), and the resultant reports thus do not conform to modern expectations of precise reporting, or have only been surveyed or subjected to test excavations, resulting in preliminary reports that did not have enough data for the authors to feel comfortable providing absolute numbers. Since even the more recent site reports are vague in their terminology, the description here also has to remain a little vague. The ceramic forms usually associated with Xindian comprise double-handled jars of various proportions, single-handled cups, small-eared jars, vases, stemmed cups, bowls, and three-legged li vessels, the latter marked with corded ware impressions. Other vessel types are often decorated with black (or, more rarely, black-and-red) geometric, zoomorphic or anthropomorphic designs, in some cases applied on thick white or red slip over often very coarse reddish-brown bodies. Painted motifs are quite striking and include triangles, net patterns, interlocking T-shaped patterns, thin hook shapes, and meandering bands. Sometimes the rims are decorated with fingertip-impressed appliqué strips. In what is deemed to be the latter part of this period, vessels with decorative bands executed in black or black-brown paint covering larger parts of high-shouldered double-handled jars begin to appear (Xie, 2002). The black or black-brown paint is often applied over corded ware and/or purple, white, orange, or red slip. The patterns are often arranged in decorative bands, mostly horizontal ones on the upper part of the vessel, but sometimes joined by vertical ones on the lower part. Additionally, some vessels carry stick-figure-like paintings of birds, dogs, sheep/goat, other four-legged animals, people, and sun symbols, usually arranged in between the ‘mustaches’ (double hooks/horns) or other broad-stroked decorations (Fig. 2).

It is important to note that thus far, Xindian culture excavations have only been conducted at 11 sites in Gansu and four sites in Qinghai Province. In Gansu these are: Xindian 辛店, Huizui(wa) 灰嘴屲, and Sishiding 四十定 (all excavated by Andersson in the 1920s); Zhangjiazui 张家咀 (Zhongguo, 1980a); Jijiachuan 姬家川 (Zhongguo, 1980a); Lianhuatai 莲花台 (Zhongguo, 1980b; Gansusheng & Beijing, 1988); Yatou 崖头 (Gansusheng, 1981); Maluyuan 马路塬 (Zhang & Pu, 1985); Yanchang 盐场 (unpublished; mentioned in Shui, 2001, p. 205); Heitouzui 黑头咀 (Huanghe, 1959); and Shizhaocun 师赵村 (Zhongguo, 1999). In Qinghai they are: Hetaozhuang Xiaohandi 核桃小旱地 (Qinghaisheng, 1995); Liuwan 柳灣 (Qinghaisheng & Zhongguo, 1984); Huzhu Zongzhai 互助总寨 (Qinghaisheng, 1986); and Bojizhang 簸箕掌 (Gao & Wu, 1984).

Few residential remains have been unearthed and only two known structures have been documented. The best preserved is from Jijiachuan (F2): a semi-subterranean rectangular pit, roughly 5 × 3 m in area, which included a ramped doorway facing east. The floor contained a layer of hard soil composed of a mixture of lime and earth and its center contained a small hearth. Remains of postholes and decayed wood led the excavators to reconstruct a structure made of wooden frame and walls mixed with earth and grass (Zhongguo, 1980a, pp. 205–206). In contrast, hundreds of pits have been found in Xindian residential zones. For example, at Lianhuatai 莲花台, over 200 pits were excavated containing a wide range of artifacts including ceramics vessels, stone and bone tools, and a circular pit where a male and female were buried side by side (Zhongguo, 1980b, pp. 297–298).

The majority of archaeological work has focused on the excavation of graves and cemeteries and the documentation of evolving burial customs. Xiaohandi 小旱地 is one of the largest excavated Xindian cemeteries with 367 graves (Qinghaisheng, 1995). The burials are mostly simple rectangular pits oriented northeast and southwest. Altogether 93 graves have been reported as having some internal furnishings, mostly wooden coffins. On a few occasions (the report does not specify how many) a two-layered coffin is interred, nearly always associated with a stepped ledge (ercengtai 二层台). The dead were placed in a supine position, with hands placed on the abdomen and the head facing to the right or left of the body. The majority of interments (277) were secondary burials, and 82 were primary burials; 358 were individual burials, but there was also one double burial and 8 cenotaphs. Where skeleton positions could be made out, supine burials were the most common (78) but in most cases the exact position was unclear. All but 16 graves contained burial goods, typically ceramic vessels. The most common ceramic type is the double-handled guan jar, along with basins (pen), vats (weng), and hu pots. The Xiaohandi cemetery contains a high number of painted pottery vessels: over 90% of the assemblage contained painted decorative elements, mostly comprising geometric patterns or the famous deer antlers/moustache motifs (Qinghaisheng, 1995, p. 5, and see Fig. 3). Some burials also contain stone and bone tools as well as animal bones but this is unusual; more common is the inclusion of items for body decoration. Such ornaments are often the most abundant artifact type placed in a grave. One particularly rich grave contained more than 600 stone beads, as well as dozens of bone and metal pao ornaments—small metal objects that may have been bosses added to clothing or other materials (Qinghaisheng, 1995, p. 10).

In addition to the shaft-pit burial form, other burials containing Xindian-style materials include intricate multi-chamber catacomb tombs (Xie, 1985). Ma (2013) has argued that this tradition was most commonly produced during the early second millennium BC (the Late Qijia culture, Early Siba culture, and Early Kayue culture), but was preserved, to some extent, during the Xindian period. Ultimately, Ma argues, the practice may have been transmitted to members of the Zhou ethnic group from people to the west. Sporadic evidence of such contact can be seen in the form of Xindian vessels found in Baoji (Lu, 1985), though its intensity and character remain unclear. A third burial form appearing at Xindian sites consists of secondary burials containing multiple disarticulated individuals (some missing their skull), such as those found in pits at Lianhuatai (Gansusheng & Beijing, 1988) and Yatou 崖头 (Gansusheng, 1981). Cheng (2006) contends that what was first considered to be the result of poor preservation and later disturbance was actually an intentional interment rite. In fact, this practice is so prevalent that Chen argues it should be considered the main burial custom for the Qinghai and Northern Gansu region. Indeed, the site of Lajia 喇家 contained a number of post-Qijia graves where secondary burials and multiple burials where found in oval-shaped graves (Minhe, 2015), though some have questioned their identification as Xindian culture (Ren, 2017).

This overview of the Xindian—with the vast majority of the data derived from mortuary contexts—provides a near-exhaustive account of this archaeological culture. By itself it illustrates a concern with identifying chronology and, to some extent, shared cultural practices that imply some sort of shared identity. This sort of summary does not, however, provide insights into economic or social practices. We now turn to discussing how Xindian people and economy have been presented, paying special attention to the impact a changing environment is believed to have had on previous subsistence lifeways.

The basic background of the geographical extent, chronological range, and homogeneity (or heterogeneity) of Xindian materials and associated practices in previous research lacks discussion of community forms or subsistence practices, except for the aforementioned assumptions concerning a transition toward pastoralism. It has been assumed that the groups creating and using Xindian-style ceramics relied on cereal agriculture, though caprine husbandry is also believed to have gained increased importance over time (e.g., An et al., 2005; Liu & Feng, 2012; Shui, 1989; Wu & Liu, 2004; Xie, 2002, p. 179; Xu, 1988; Yang et al., 2019a, 2019b). The basis for the reliance on cereal agriculture and caprines is the combination of a considerable number of agricultural tools at Lianhuatai, Jijiachuan, Zhuangjiazui and similar sites, along with limited zooarchaeological evidence of domesticated sheep and goat. At Zhangjiazui the excavators note a large number of bone and stone tools at the site suited for a wide range of agricultural practices (Zhongguo, 1980a, pp. 216–217). Some stone and bone tools have long and thin blades suitable for tilling the earth, and the site contains many mortars and pestles, possibly for processing grains (Zhongguo, 1980a, p. 215). Previous archaeobotanical analyses from sites in the Guangting Basin, Qinghai (preliminarily assigned to the Xindian culture) have shown the presence of broomcorn and foxtail millet, barley, wheat, hemp, and other plants (Zhang, 2012, p. 28). Whereas Qijia sites in the same region contained a larger proportion of foxtail millet, the remains purported to be related to Xindian materials contain more broomcorn millet, and the investigator interprets this as a switch brought on by the onset of drier conditions (Zhang, 2012, p.30).

The combination of a seed density much lower than at Qijia sites, and large amounts of animal bones, especially sheep/goat (Zhang, 2012, p. 31; Zhongguo, 1980a, p. 210), has led some scholars to argue for a decline in intensity of cereal agriculture and a shift toward a mixed subsistence economy (e.g. Hou et al., 2009). The finding of hooks and nets further suggests inhabitants may have supplemented their diet with deer and fish (Zhongguo, 1980a, p. 220). Indeed, Xindian sites so far have yielded sheep/goat, pig, cattle, dog, and sometimes horse bones, as well as deer. Recent isotopic analysis of two herbivore bones from Wenjia showing a C₄ signature suggests that domesticated animals, possibly sheep/goat or bovids, may have been fed agricultural crops, given that this signature would reflect millet consumption but does not correspond to the background C₃ plants that are common in the region (Ma et al., 2016, p. 26; see also Barton et al., 2009, p. 5524). This would not be a surprising result given the practice of foddering domesticated animals with millet, shown isotopically elsewhere in the North China Neolithic (Barton et al., 2009; Chen et al., 2015; Dai et al., 2016a, 2016b), but the small sample size demands caution. At present, these can only be preliminary suggestions.

Changes or continuities in subsistence between the Qijia and Xindian communities should be considered in relationship to broader environmental trends during the second millennium BC. The past decade has seen a rise in deterministic models focusing on climate change. One example, variously termed the ‘ ~ 4.2 k BP event’ (a term borrowed from the Near East), the ‘c. 4000 cal yr BP climatic event’, and the ‘Holocene event 3’ is understood to represent a phase of global environmental stress (at least in the northern hemisphere), which had wide-scale social, political and economic implications as its effects were differentially felt over centuries (e.g. Booth et al., 2005; Dalfes et al., 1997; deMenocal, 2001; Hsu & Perry, 2002; Meller et al., 2015). In the region of concern in this article, some scholars have associated this period of climate stress with cultural change, including employing the event to explain the transition from Qijia (c. 2200–1500 BC/4150–3450 BP) to subsequent cultures. In such discussions, Xindian (c. 1600–600 BC/3550–2550 BP), along with Kayue (c. 1800–1500 BC/3750–3450 BP), Siba (c. 1950–1550 BC/3900–3500 BP) and Siwa (c. 1300–500 BC/3250–2450 BP) are seen as communities practicing pastoral nomadism. This line of argument proposes that in regions of northern China including Inner Mongolia, Qinghai and Gansu, a prolonged period of aridity and cooler temperatures eventually resulted in the collapse of many existing societies, as well as a transition from cereal agriculture to pastoral or agro-pastoral communities (e.g. An et al., 2005; Liu & Feng, 2012; Wu & Liu, 2004).

Although called an ‘event,’ the 4.2 k BP variation is in reality a multi-centennial scale transition to cooler and drier conditions that have been noted in several proxies (see e.g.: Dykoski et al., 2005; Hou et al., 2016; Kaufmann et al., 2020; Liang et al., 2020; Marcott et al., 2013; Wang et al., 2005; Zhao et al., 2009). The onset of cooler and drier conditions is at roughly 4200 cal BP and is followed by a continued decline in both temperature and precipitation—though recent work has highlighted subsequent multi-decadal oscillations, as well as regional-specific spatiotemporal variations (e.g. Cai et al., 2017; Railsback et al., 2018; Tan et al., 2018; Zhang et al., 2018a, 2018b). Multi-proxy modelling by d’Alpoim Guedes and Bocinsky (2018) suggests that these reach their lowest point at 3600 BP, after which temperatures increase slightly, but never again reach the high levels of the earlier Holocene climatic optimum. Although on a geological scale this process is rather short, in relation to cultural change, the hundreds of years over which changes occur and would have been perceived by people is quite significant. Recognizing the multi-centennial scale of this transition calls into question some of the arguments for abrupt cultural changes directly tied to this event in some of the literature (e.g. Liu & Feng, 2012; Wu & Liu, 2004).

Another aspect of the problem is the confusion in the literature over the timing of the beginning and end of the Qijia culture (see overview in Jaffe & Flad, 2018). Most existing data on the cultural chronology would place the beginning of the Qijia period roughly around the same time as the onset of this climatic event (i.e., around 4200 BP). It is noteworthy that the Qijia phenomenon did not suddenly appear across the entire region where we ultimately find Qijia remains. Instead, earlier Qijia sites are found in the more eastern parts of the overall distribution, while later in the sequence, areas like the Tao river are occupied. The overall chronological range for the Qijia culture, which we list as c. 2200–1500 BC/4150–3450 BP, much less the entire distribution range of the Qijia culture, cannot necessarily be ascribed in its entirety to any one region.

When the so-called collapse of the Qijia culture has been most explicitly attributed to the events of ~ 4000 cal. yr BP and the replacement of dry farming with pastoral subsistence practices by the cultures that followed it (Mo et al., 1996; Shui, 2001) scholars seem to be engaging in one of two processes. They are either modifying cultural chronologies to fit assumptions about the effects of environmental change or they are accepting uncritically the chronological scope of an archaeological culture to apply uniformly across the region where associated sites are found (and see Jaffe et al., 2020). In the case of some scholarship that has associated the collapse of Qijia and the onset of Xindian and other cultures with the 4.2 k BP event, we consequently see an adoption of a short chronology for the Qijia culture. For example, for An et al. (2005), the Qijia culture is dated to 4300–3900 cal BP, and they propose that while the associated society flourishes early on, marked by the development of sophisticated technologies and larger site numbers and regional distribution, it collapses quickly after the ~ 4000 cal. yr BP event (note that here the event is referenced as c. 4000 cal yr BP, rather than 4.2 k BP). Liu and Feng (2012), in contrast, place the Qijia dates at 4000–3800 cal. yr BP, yet similarly find that the Qijia culture flourishes during its initial phases but soon declines due to the continued effects of this climatic event. In this narrative, the Qijia are succeeded, after an additional hiatus of 200 years, by a number of different cultures, each occupying its respective zone more sparsely and exhibiting cultural atavism or the reversal of the advances of the preceding culture.

Conversely, Liu et al. (2010) extend the duration of the Qijia culture from 4000 to 3600 BP and note the more severe climatic influences (extremely low temperatures), which characterized the period from 3.9–3.6 k BP. In this argument the prolonged effects of the climatic event slowly chipped away at Qijia society until it collapsed around 3600 BP, resulting in a separation of nomadism from farming. The turn to an increased emphasis on pastoral economic practices was followed, they believe, by most subsequent societies, but to varying degrees based on the environmental zone of those cultures that succeeded it: from pastoral nomadism of the Kayue in Qinghai, to a mixed agro-pastoral economy of the Siwa culture in the higher altitudes of Southwest Gansu, and the survival of farming in the Xindian culture occupying the moderately warmer climate of the Yellow River valley.

As noted above, the available archaeological evidence for the Qijia and subsequent periods remains scarce, rendering testing the above models problematic. Furthermore, the archaeological data currently available is mostly from graves and can thus provide limited insight into supposed subsistence changes (Jaffe & Hein, 2020). Only a handful of sites have been excavated sufficiently to show catastrophic events—the exception being the site of Lajia in Qinghai Province, where the Qijia period levels were destroyed by a cataclysmic flash flood and/or earthquakes, burying inhabitants alive at c. 3950 cal. BP (Zhang et al., 2018a, 2018b). This catastrophic event may have impacted a number of communities along the Yellow River (Huang et al., 2013; Wu et al., 2016; c.f. Wu et al., 2017), however, it does not necessarily reflect a regional climatic shift that would have had widespread impacts on the economic and social practices of Qijia communities more generally. Moreover, others argue that the lake proposed to be responsible for the dam-burst flood had already disappeared by c. 3600 BC (i.e., c. 5600 cal. BP, more than 1600 years earlier), and that other skeletal remains from the site date to the period between 1875 and 1662 cal BC (i.e., 3825–3612 cal BP; Dong et al., 2018). Accordingly, flooding may have occurred less catastrophically, but perhaps frequently, over a drawn-out period of several hundred years.

The dates at Lajia also demonstrate Qijia cultural dates in the western part of the Qijia distribution closer to 1600 cal. BC (3550 cal. BP). Our work at the site of Qijiaping 齐家坪, roughly 250 km southeast of Lajia, has uncovered Qijia-culture occupation that ranges between 1631 and 1431 cal. BC (3581–3381 cal. BP) based on 12 dates from two pits (Brunson et al., 2020; Womack et al., 2021). The data from Qijiaping imply a flourishing of Qijia culture in the Tao river region in a 150-year period, and combined with other Qijia culture contexts in the Tao River valley, such as the site of Mogou (Gansu & Xibei, 2009), these data show an intensity of occupation in the Tao river valley at the time when others have suggested that Qijia is collapsing, possibly because people may have migrated there from other regions. Even recognizing that the climate changes that began at 4200 BP took a long time to impact communities in different areas, in the Tao river valley the impacts may have been very different from elsewhere.

Indeed, given the multi-centennial nature of climate change human societies do not demonstrate uniform, clear-cut strategies in response to specific climatic events (Haldon et al., 2018; Izdebski et al., 2016; Jaffe et al., 2019; Meltzer, 2015). In Northeastern China, the onset of the ~ 4000 cal. yr BP event was followed by a distinct flourishing of society during the Lower Xiajidian 夏家店下层 period (c. 2200–1600 BC/4150–3550 BP), when the region was densely populated by large and stable communities practicing subsistence agriculture (Chifeng, 2011; Shelach, 2009). Might a similar florescence have occurred during the later part of the Qijia or even post-Qijia instead of the full scale transition to pastoralism that has been proposed? Careful study combining improved models (d’Alpoim Guedes et al., 2016a, 2016b; Goldsmith et al., 2017) of site-specific (Zhuang & Kidder, 2014), region-specific (Su & Kidder, 2019), and historical data (Haldon et al., 2018; Pederson et al., 2014) are needed for an accurate understanding of human–environment dynamics (McAnany & Yoffee, 2009; Redman, 2005; Tainter, 2006). As a first step, we need to start with a basic understanding of the local chronology and the region-specific sequential cultural and economic manifestations.

What we can say with the evidence at hand is that the Qijia culture flourished during its later phases in the western portions of the broader Qijia cultural range, including in the lower Tao River valley, until as late as c. 1431 cal. BP/3381 cal. BP. Following the occupation of Qijia culture sites in this valley, including the culture type-site of Qijiaping (Womack et al., 2017, 2021), the area is occupied by communities creating ceramics of the Xindian cultural tradition. The distribution of Xindian sites displays a relatively clear geographical pattern in the Tao River valley. Xindian sites are found in the northern, lower reaches of the river valley between 1700 and 2100 masl. Further south, sites that post-date the Qijia culture are associated with the Siwa tradition, mostly distributed at elevations of 2000–2700 masl, generally higher than Xindian sites (and see Womack et al., 2021).

We must be cautious not to overemphasize the above trend/elevation association, as it is obtained from sites found in unsystematic surveys over the past few decades (and see Jaffe et al., 2020). Yet based on these distributions, we might expect that in addition to having different ceramic styles, the communities associated with Siwa and Xindian materials may have had different economic foci. Likewise, the differences between Qijia and Xindian cultural traditions, which are based primarily on shared practices in ceramic production and, to a lesser extent, mortuary practices, may also reflect chronological changes in settlement organization and subsistence practices. In order to assess this possibility, however, baseline data is required concerning the organization of Xindian settlements and the nature of subsistence practices at these sites. Two known Xindian culture sites have been examined by the TRAP project to help develop this baseline: Xindian and Huizuiwa.

A large number of studies have reconstructed the second millennium BC economy of the upper Yellow River as one dominated by pastoralism—possibly even involving semi-sedentary populations and more ephemeral settlements. In part, this assumption of pastoralism may reflect a tendency to perceive prehistoric societies inhabiting the upper Yellow River valley as others to their ‘Chinese’ counterparts situated in the Central Plains and adjacent regions. Yet, to date, research has relied on data derived from a limited number of excavated cemeteries, cursory survey data and a handful of residential contexts, severely limiting the ability to evaluate these models.

The work discussed in this paper brings together systematic survey results and their analysis in ArcGIS, magnetometer investigation, excavation and the analytical exploration of ceramic, faunal and floral remains, including a series of stratified radiocarbon dates. Together, they offer windows into past lifeways of the communities inhabiting these regions during this time. Our finds, while limited, further enable us to evaluate existing narratives of 2nd millennium BC societies in the region. Mostly, they caution against approaches that would view this large region as uniformly occupied by identical communities who subsisted on the same economic practices.

The results of our work do not show a whole-scale transition in subsistence and cultural practices following the 4.2 k BP event. When compared with results at Qijiaping and other earlier sites, Xindian activities show selective uptake of new crops and animals, but also a continuation of older practices. Xindian activities in this region took advantage of the opportunities presented by environmental changes, social dynamics, and interregional interaction that were available in an ever-changing world. Xindian communities in the broader western regions show no evidence of being incorporated into the centralizing political dynamics of Bronze Age China further to the east.

The Tao River Archaeology Project has aimed to create a model for gathering robust archaeological information that can solidify our base-line understanding of economic, technological, and social practices in the third through early first millennia BC. We hope that future research, which similarly incorporates survey data, geophysical prospection, and excavations, will increase our understanding of these domains of activity, and further refine the chronology of settlements and communities in this region, allowing the further exploration of broader social dynamics in prehistoric Northwestern China.