Censuses taken during the Sui and Tang dynasties provide some evidence as to population changes. Surviving figures for 609 and 742, representing two of the most complete of the earlier Chinese population registrations, give totals of some 9 million households, or slightly more than 50 million persons. Contemporary officials considered that only about 70 percent of the population was actually registered, so the total population may have been as much as 70 million.

Between 609 and 742 a considerable redistribution of population took place. The population of Hebei and Henan fell by almost one-third because of the destruction suffered at the end of the Sui era and in the invasions of the 690s and because of epidemics and natural disasters. The population of Hedong (present-day Shanxi) and of Guanzhong and Longyou (present-day Shaanxi and Gansu, respectively) also fell, though not so dramatically. The population of the south, particularly the southeastern region around the lower Yangtze, took a leap upward, as did that of Sichuan.

Whereas under the Sui the population of the Great Plain (Hebei and Henan) had accounted for more than half of the empire’s total, by 742 this had dropped to about one-third. The Huai-Yangtze area, which had contained only about 8 percent of the total in 609, now contained one-fourth of the entire population, and Sichuan’s share jumped from 4 percent to 10 percent of the total, exceeding the population of the metropolitan province of Guanzhong. The increase in the south was almost entirely concentrated in the lower Yangtze valley and delta and in Zhejiang.

The revolt of An Lushan and Shi Siming and his son Shi Chaoyi (755–763) precipitated more population movements from north to south, with some of these migrants penetrating into what is now southern Hunan and beyond. These shifts then and later in the Tang considerably redistributed China’s population: the south became more populous than the north, and the populations among regions in the south became more balanced.

There are no reliable population figures from the late Tang era, but the general movement of population toward the south certainly continued, notably in the area south of the Yangtze, in present-day Jiangxi and Hunan, and in Hubei. The chaos of the last decades of the Tang dynasty completed the ruin of the northwest. After the destruction of the city of Chang’an in the Huang Chao rebellion, no regime ever again established its capital in that region.

Growth of the economy

The 8th and 9th centuries were a period of growth and prosperity. The gradual movement of the population away from the north, with its harsh climate and dry farming, into the more fertile and productive south meant a great proportional increase in productivity. The south still had large areas of uninhabited land. Fujian, for example, was still only marginally settled along the coastline at the end of Tang times. During the latter half of the Tang, the Huai and lower Yangtze became a grain-surplus area, replacing Hebei and Henan. From 763 to the mid-9th century, great quantities of grain were shipped from the south annually as tax revenue. New crops, such as sugar and tea, were grown widely. The productivity of the Yangtze valley was increased by double-cropping land with rice and winter wheat and by developing new varieties of grain. After the An Lushan rebellion, silk production began to increase rapidly in Sichuan and the Yangtze delta region, whereas in early Tang times the chief silk-producing areas had been in the northeast.

A boom in trade soon followed. The merchant class threw off its traditional legal restraints. In early Tang times there had been only two great metropolitan markets, in Chang’an and Luoyang. Now every provincial capital became the center of a large consumer population of officials and military, and the provincial courts provided a market for both staple foodstuffs and luxury manufactures. The diversification of markets was still more striking in the countryside. A network of small rural market towns, purely economic in function and acting as feeders to the county markets, grew up. At these periodic markets, held at regular intervals every few days, traveling merchants and peddlers dealt in the everyday needs of the rural population. By the end of the Tang period these rural market centers had begun to form a new sort of urban center, intermediate between the county town, with its administrative presence and its central market, and the villages.

The growth of trade brought an increasing use of money. In early Tang times silk cloth had been commonly employed as currency in large transactions. When the central government lost control of the major silk-producing region in Hebei and Henan, silk was replaced in this use by silver. The government neither controlled silver production nor minted a silver coinage. Silver circulation and assay were in the hands of private individuals. Various credit and banking institutions began to emerge: silversmiths took money on deposit and arranged for transfers of funds; a complex system of credit transfers arose by which tea merchants would pay the tax quota for a district, sometimes even for a whole province, out of their profits from the sale of the crop at Chang’an and receive reimbursement in their home province.

The increasing use of money and silver also affected official finance and accounting. Taxes began to be assessed in money. The salt monopoly was collected and accounted for entirely in money. The government also began to look to trade as a source of revenue—to depend increasingly on taxes from commercial transactions, levies on merchants, transit taxes on merchandise, and sales taxes.

The most prosperous of the merchants were the great dealers in salt, the tea merchants from Jiangxi, the bankers of the great cities and particularly of Chang’an, and the merchants engaged in overseas trade in the coastal ports. Foreign trade was still dominated by non-Chinese merchants. Yangzhou and Guangzhou had large Arab trading communities. The northern coastal traffic was dominated by the Koreans. Overland trade to Central Asia was mostly in the hands of Sogdian and, later, Uighur merchants. Central Asian, Sogdian, and Persian merchants and peddlers carried on much local retail trade and provided restaurants, wine shops, and brothels in the great cities. Only in the 9th century did the foreign influence in trade begin to recede.

In the late Tang many officials began to invest their money (and official funds entrusted to them) in commercial activities. High officials took to running oil presses and flour mills, dealing in real estate, and providing capital for merchants. The wall between the ruling class and the merchants that had existed since the Han period was rapidly breaking down in the 9th century, and the growth of urbanization, which characterized the Song period (960–1279), had already begun on a wide scale.