7. The Relationship between Climate Change and the Interaction between Sedentary and Nomadic Groups in Northern China over the Past 2000 Years

“Nomadic pastoralism” and “sedentary farming” are two main modes of economic production and social life in ancient China, forming two different types of civilizations named nomadic and sedentary. The ethnic relations between sedentary and nomadic groups written by “war” and “peace”, under the background of climate change, were an important part of the history of Chinese civilization. Based on historical literature records, the sequences of war and peace-making events between sedentary farming and nomadic pastoral groups were constructed. There are 832 wars from the Western Han Dynasty to the Qing Dynasty. Dynastic statistics reveal that the frequency of nomadic-sedentary wars during the Eastern Han, Western Jin, Eastern Jin, Song, and Ming dynasties far exceeded the average level. From 210 BCE to 1910 CE, a total of 504 peace-making events were recorded. The frequency of peace-making events was much higher than average in the Northern and Southern Dynasties, Sui, Five Dynasties and Ten Kingdoms, Northern Song and Qing dynasties. Wars occurred more frequently during the warm phases and less frequently in cold phases and the frequency was positively correlated with temperature anomalies. While the frequency of peace-making events was negatively correlated with temperature anomalies, contrary to the trend of more wars in warm phases and fewer in cold phases.