Extensive internal migration, improving communications and many centuries of unity or near unity helped to foster a relatively homogeneous culture across what was, for its time, a massive population. The Qin dynasty, short though its life may have been, constructed over 4,000 miles of imper-ial highways, as many as the Roman Empire. [197] A centralized state, and a sophisticated statecraft, took root based on the teachings of Confucius (551-479 BC), who was to exercise a huge influence over the Chinese political and moral universe for more than two millennia. Weights, measures and currency were standardized. The distinctive customs that we associate with China – including the mandate of Heaven, a family structure resting on filial piety, a language that used common signs and symbols, and a religion based on ancestral worship – were well established by the time of the Qin dynasty. During the first millennium AD, therefore, China was to acquire – given the fact that in practice it embraced many different peoples – an unusually strong sense of cultural identity. [198] One of the most striking features of Chinese history has been that, although it has been invaded from the north many times – notably by the Mongols in the thirteenth century and the Manchu in the seventeenth – all invaders, bar the Mongols, once secure in power, sought to acquire the customs and values of the Chinese and to rule according to their principles and their institutions: a testament to the prestige enjoyed by the Chinese and the respect accorded to their civilization by their northern adversaries. [199] The persistence and steady spread of the Chinese language is a further indication of the strength of the culture: the constant invasions from the north, by obliging the population to stay mobile, kept the language from becoming atomized into different dialects, at the same time making the Chinese themselves more aware of, and therefore also protective of, both their language and culture. [200] The early emergence of a Chinese identity is, perhaps more than anything else, the key to China as we know it today, for without that, China could not have remained a relatively unified country for over two millennia and would have been shorn of its most striking characteristic: its size.
Map 5. Boundary of the Qin Dynasty at its Greatest Extent, c.206 BC
Map 6. Boundary of the Han Dynasty at its Greatest Extent, 141-87 BC
Historically, relatively advanced forms of agriculture enabled societies to sustain large populations and provided propitious conditions for the development of organized states; China was a classic example of this phenomenon. It is now believed that millet and rice first appeared in northern and southern China respectively 12,000 years ago, earlier even than in Mesopotamia, where sedentary agriculture began about 8,000 years ago. Although North China has long sustained ‘dry’ agriculture by way of cereals, barley and various kinds of millet, it was the wet cultivation of rice, which developed slowly from the beginning of the first millennium and which was in full swing by its end, that was later to give a major boost to Chinese agriculture, resulting in a shift in the economic centre of gravity from the central plain to the lower Yangzi basin. New methods of wet rice cultivation were introduced, including the planting of seedlings, early ripening varieties of rice, the systematic selection of species, new tools such as a chain with paddles which made it possible to lift water from one level to another, and sophisticated forms of irrigation. These made Chinese wet rice farming one of the most advanced agricultural techniques in the world, generating extremely high yields. [201] During the Song dynasty (AD 960-1279), these advanced techniques were generalized across large tracts of the country, pushing south as the frontier was steadily extended. [202] Sustained by agrarian prosperity, the population expanded rapidly, almost doubling between 1000 and 1300. [203] Between AD 500 and 900 bricked roads were built across the middle of the Chinese empire such that the capital (known then as Chang’an, now as Xi’an) was only eight to fourteen days’ travel from any reasonably sized city. Even more significant was the spread of water transport in the form of rivers, canals and coastal shipping. These various waterway systems became part of an integral network that was to form the basis of a nationwide market that steadily took shape by 1200. As Marco Polo, a resident of Venice, Europe ’s greatest seaport, observed of the Yangzi in the late thirteenth century:
