East Asian scholars have begun only recently to examine Chinese, Korean, and Japanese sources for evidence of the history of disease in East Asia. Research is at a very early stage: There is much that we do not know, and some of what we think we know may turn out to be wrong. At present, scholars disagree about basic facts as well as about how to interpret them. It is possible, however, to discuss how disease ecologies changed as East Asian civilization developed, and this essay will consider how long-term historical change in East Asia altered the disease ecologies of this major world region.

East Asia is a large ecological niche bounded on all sides by less hospitable terrain. To the north and northwest lie the vast steppe lands of Central Asia and the virtually impossible Takla Makan Desert. To the west lie the high Tibetan Plateau and the Himalayan Range with the world’s highest mountains. To the south is the mountainous terrain of southwest China and the jungles of Southeast Asia. And to the east lies the Pacific Ocean. These formidable barriers and the great distances between eastern and western Eurasia long separated East Asia from the ancient civilizations of the West, and permitted a distinctive culture to develop and to spread throughout the region with relatively little influence from the outside.

East Asia can be divided into two major ecological zones. The northern zone encompasses the steppe and forest lands that lie north of China’s Great Wall and today includes the modern regions of Inner Mongolia and Manchuria.