The central government under Wendi developed into a complex apparatus of ministries, boards, courts, and directorates. The conduct of its personnel was supervised by another organ, the censorate. The emperor presided over this apparatus, and all orders and legislation were issued in his name. He was assisted by the heads of the three central ministries who acted as counselors on state affairs (yiguozheng). That system later provided the basic framework for the central government of the early Tang.
Even more important, he carried out a sweeping reform and rationalization of local government. The three-level system of local administration inherited from Han times had been reduced to chaos during the 5th and 6th centuries by excessive subdivision; there were innumerable local districts, some of them extremely small and dominated by single families. Wendi created a simplified structure in which a much reduced number of counties was directly subordinated to prefectures. He also rationalized the chaotic rural administrative units into a uniform system of townships (xiang). Appointments to the chief offices in prefectures and counties were now made by the central government rather than filled by members of local influential families, as had been the practice. This reform ensured that local officials would be agents of the central government. It also integrated local officials into the normal pattern of bureaucratic promotion and in time produced a more homogeneous civil service.
Since the registration of population had fallen into chaos under the Bei Zhou, a careful new census was carried out during the 580s. It recorded the age, status, and landed possessions of all the members of each household in the empire, and, based on it, the land allocation system employed under the successive northern dynasties since the end of the 5th century was reimposed. The tax system also followed the old model of head taxes levied in grain and silk at a uniform rate. The taxable age was raised, and the annual period of labour service to which all taxpayers were liable was reduced.
Wendi’s government, in spite of his frontier campaigns and vast construction works, was economical and frugal. By the 590s he had accumulated great reserves, and, when the Chen territories were incorporated into his empire, he was in a position to exempt the new population from 10 years of taxes to help ensure their loyalty.
The military system likewise was founded on that of the northern dynasties, in which the imperial forces were organized into militias. The soldiers served regular annual turns of duty but lived at home during the rest of the year and were largely self-supporting. Many troops were settled in military colonies on the frontiers to make the garrisons self-sufficient. Only when there was a campaign did the costs of the military establishment soar.
Integration of the south
The second Sui emperor, Yangdi (reigned 604–617/618), has been depicted as a supreme example of arrogance, extravagance, and personal depravity who squandered his patrimony in megalomaniac construction projects and unwise military adventures. This mythical Yangdi was to a large extent the product of the hostile record written of his reign shortly after his death. His reign began well enough, continuing the trends begun under Wendi; a further revision of the law code that generally reduced penalties was carried out in 607.
Yangdi’s principal achievement was the integration of the south more firmly into a unified China. There is little evidence that the south was ever completely brought into line with all the administrative practices of the north; the land allocation system seems unlikely to have been enforced there, and it is probable that the registration of the population, the essential foundation for the whole fiscal and military system, was only incompletely carried out in the old Chen territories. However, Yangdi himself was personally heavily involved with the south. Married to a princess from the southern state of Liang, he had spent 591–600 as viceroy for the southern territories; their successful integration into the Sui empire after the initial wave of risings was largely because of his administration and the generally clement policies employed in the former Chen territories.
His identification with the southern interest was one of the reasons he began establishing an examination system, based upon the Confucian Classical curriculum, as a means of drawing into the bureaucracy scholars from the southern and northeastern elites who had preserved traditions of Confucian learning. Hitherto, the court had been dominated by the generally less cultivated aristocratic families of mixed ancestry from northwestern China.
Yangdi also attempted to weaken the predominance of the northwest by building a second great capital city at Luoyang, on the border of the eastern plains. This capital was not only distant from the home territories of the northwestern aristocrats but also easily provisioned from the rich farmlands of Hebei and Henan. The new city was constructed in a great hurry, employing vast numbers of labourers both in building and in transporting the timber and other materials required. Yangdi also built new palaces and an immense imperial park, again with a prodigal use of labour.
Another grandiose plan aimed at unifying the empire was to develop still further the canal system his father had begun in the metropolitan region and to construct a great waterway, the Bian Canal, linking Luoyang with the Huai River and with the southern capital, Jiangdu (present-day Yangzhou), on the Yangtze. Much of this route followed existing rivers and ancient canals, but it was still an immense undertaking that employed masses of forced labourers working under appalling conditions. In 605 the canal system was opened between the capital at Luoyang and the Yangtze, and in 610 it was extended south of the Yangtze to Hangzhou as part of a general effort to rehabilitate and lengthen the Grand Canal. At the same time, in preparation for campaigns in Manchuria and on the Korean frontier, another great canal was built northward from Luoyang to the vicinity of modern Beijing. By 611 the entire eastern plain had a canal system linking the major river systems of northern China and providing a trunk route from the Yangtze delta to the northern frontier. The construction of these waterways was inordinately expensive, caused terrible suffering, and left a legacy of widespread social unrest, but in the long term the transportation system was to be a most important factor for maintaining a unified empire. Further hardship was caused by the mass levies of labour required to rebuild and strengthen the Great Wall in Shanxi in 607 and 608 as a precaution against the resurgent eastern Turks.
Foreign affairs under Yangdi
In addition to these farsighted construction works, Yangdi also pursued an active foreign policy. An expedition to the south established sovereignty over the old Chinese settlement in Tongking and over the Champa state of Lin-yi in central Nam Viet (present-day Vietnam). Several expeditions were sent to Taiwan, and relations with Japan were opened. Tuyuhun people were driven out of Gansu and Qinghai, and Sui colonies were established along the great western trade routes. The rulers of the various petty local states of Central Asia and the king of Gaochang (Turfan) became tributaries. A prosperous trade with Central Asia and the West emerged.
The principal foreign threat was still posed by the Turks. By the early 7th century, these peoples had been completely split into the eastern Turks, who occupied most of the Chinese northern frontier, and the immensely powerful western Turks, whose dominions stretched westward to the north of the Tarim Basin as far as Sāsānian Persia and Afghanistan. During the early part of Yangdi’s reign, the western Turks, whose ruler, Chuluo, was half-Chinese, were on good terms with the Sui. In 610, however, Yangdi supported a rival, Shegui, who drove out Chuluo. The latter took service, with an army of 10,000 followers, at Yangdi’s court. When Sui power began to wane after 612, the western Turks under Shegui gradually replaced the Sui garrisons in Central Asia and established control over the states of the Tarim Basin. The eastern Turks had remained on good terms with the Sui, their khans being married to Chinese princesses. In 613 Pei Ju, Yangdi’s principal agent in dealing with the foreign states of the north, attempted unsuccessfully to dethrone the eastern Turkish khan and split up his khanate. Relations with the Turks rapidly deteriorated, and in the last years of his reign Yangdi had to contend with a hostile and extremely powerful neighbour.