As in most areas of the world, the geography of the region has had an impact on the development of Chinese civilization from ancient times to the present. China proper, about a thousand miles north to south and east to west, occupies much of the temperate zone of East Asia (Map 4.1). The northern part, drained by the Yellow River, is colder, flatter, and more arid than the south. Rainfall in many areas is less than twenty inches a year, making the land well suited to crops like wheat and millet. The dominant soil is loess — fine wind-driven earth that is fertile and easy to work even with simple tools. The soil gives the Yellow River its characteristic color, and because so much of the loess ends up as silt in the river, the riverbed rises and easily floods unless diked. Drought is another perennial problem for farmers in the north. The Yangzi (YANG-zuh) River is the dominant feature of the warmer, wetter, and more lush south, a region well suited to rice cultivation. Farmers in recent centuries have been able to get two rice crops a year from the land around the Yangzi River and farther south. The Yangzi and its many tributaries are navigable, so boats were traditionally the preferred means of transportation in the south.

Mountains, deserts, and grasslands separated China proper from other early civilizations. Between China and India lay Tibet, with its vast mountain ranges and high plateaus. North of Tibet are great expanses of desert where nothing grows except in rare oases, and north of the desert, grasslands stretch from Ukraine to eastern Siberia. Chinese civilization did not spread into any of these Inner Asian regions, above all because they were not suited to growing crops. Inner Asia, where raising animals is a more productive use of land than planting crops, became the heartland of China’s traditional enemies, such as the nomadic tribes of the Xiongnu (SHUHNG-noo) and Mongols.