ABSTRACT
The hearth of the Shang state, that ancient civilization of China (18th-12th century B.C.), was on loess soils of the north, especially in the middle course of the Yellow River (Figure 1). That region is bounded on the south and southwest by the Tsinling and adjacent mountains, east-west ranges whose peaks rise over 12,000 feet above sea level to separate the arid loess lands of North China and the green, rainy lands of Central and South China. In North China, the early Chinese were subject to recurrent pressures that led them to migrate, commonly in large, organized population movements, to the south. Those pressures were of various sorts, some environmental, some cultural. The North Chinese homeland had modest precipitation, much of it today between 30 to 40 inches annually, an amount similar to that of much of the American Great Plains. There was also considerable rainfall variability, and repeated periods of drought, famine, and pestilence, which provided powerful incentives to migrate. Another pressure was exerted by the northern neighbors of the Chinese, warlike nomads and semi nomads, such as the Hsiung-nu, who coveted the grasslands of the Chinese and who were tempted, as well, by the prospects for loot. Over the four millennia of Chinese migration to the south, one discerns other major causes as well: floods; political instability and civil war; hostility among neighboring ethnic groups; invasion and defeat by other settled states; prestige and expansion of the empire; and population increase, poverty, and desire for economic betterment. In some cases, migrations were spontaneous, and could involve movement of an entire village or even the people of an entire region. In other cases, migrations were encouraged or decreed by the authorities, and might involve dissidents, criminals, retinues of government appointees, and others.
