Sui Dynasty

The Sui rose out of the military aristocracy of north-western China that had formed during the long division of the Northern and Southern dynasties. In 577 the Xianbei-led Northern Zhou conquered the Northern Qi and reunified the north, and the general Yang Jian became regent at the Zhou court. His clan, the Yang of Hongnong, claimed Han descent from the Han dynasty general Yang Zhen but had intermarried with the Xianbei for generations. Yang Jian's daughter was the Empress Dowager and her stepson, Emperor Jing of Northern Zhou, a child. After crushing an army in the eastern provinces, Yang Jian usurped the throne in 581 and became Emperor Wen of Sui. In a bloody purge he had 59 Zhou princes eliminated, in contrast to his later reputation as the 'Cultured Emperor'.

Emperor Wen stressed Han cultural identity, abolishing the anti-Han policies of Northern Zhou and reclaiming the surname Yang, and won over the Confucian scholars by abandoning the nepotism of the nine-rank system. His reforms prepared the state for the wars that would reunify China. Thousands of boats were assembled against the Chen navy on the Yangtze, and in 588 some 518,000 troops lined the river's northern bank. In 589 Sui soldiers entered Jiankang, the last Chen emperor surrendered, and the city was razed while its nobles were escorted north.

The Sui set out to rebuild the state after centuries of division. Emperor Wen and his successor Emperor Yang pursued centralising reforms, most notably the equal-field system, which aimed to reduce economic inequality and raise agricultural productivity, the Five Departments and Six Boards system that preceded the Tang's Three Departments and Six Ministries, and the standardisation and reunification of the coinage. Like the Han, Emperor Wen established granaries both as stores of food and as a means of regulating market prices through the taxation of crops. By the dynasty's mid-point a vast agricultural surplus supported rapid population growth to a peak surpassed only under Emperor Xuanzong of Tang more than a century later.

The capital Daxing lay in the secure Guanzhong but far from the economic centres to the east and south. Emperor Wen therefore began the Grand Canal, completing first the shortest route, from Chang'an to the Yellow River; Emperor Yang enormously enlarged the work. The canal linked Luoyang with Chang'an, with the agricultural centres towards Jiangdu (now Yangzhou) and Yuhang (now Hangzhou), and with the northern frontiers near modern Beijing. Begun to move grain to the capital and to carry troops, it went on to carry domestic trade, people and ideas for centuries. These projects, with the extension of the Great Wall and the rebuilding of Luoyang, were run by an efficient bureaucracy but conscripted millions of workers at a heavy human cost.

Sui military power was first shown on the Yangtze. For the conquest of the Chen dynasty Emperor Wen built a fleet whose largest ships carried five decks and 800 non-crew personnel, with six 50-foot booms to damage enemy vessels or pin them for boarding, and in 588 massed 518,000 troops along the river from Sichuan to the East China Sea; Chen fell in 589. Xianbei, other Chinese groups and people from newly conquered south-eastern Sichuan served in the campaign. In the north the emerging Turkic Khaganate was the chief threat; Emperor Wen's diplomacy split it into Eastern and Western halves, and the Great Wall was consolidated. In his late years a first war with Goguryeo ended in defeat.

Both emperors sent expeditions into Vietnam. The Hanoi area was easily retaken from the Early Lý ruler Lý Phật Tử in 602, and the army then pushed south against the Kingdom of Champa in the Linyi-Champa Campaign of 602–605. Attacked by troops on war elephants, the Sui feigned retreat, dug pits to trap the animals and turned crossbows on them, so that the elephants trampled their own side; the victors nonetheless lost many men to malaria. Emperor Yang then led massive expeditions against Goguryeo, one of the Three Kingdoms of Korea: one force is recorded with over 3,000 warships, up to 1.15 million infantry, 50,000 cavalry and 5,000 artillery. All four expeditions failed, ending in defeat by 614 and leaving a deficit of money and manpower from which the dynasty never recovered.

The Sui re-established and reformed many imperial institutions, laying the foundation on which the Tang built; the Tang adopted the Sui political system with little initial change except at the top. The Five Departments and Six Boards organised the central government, and Emperor Wen, having abandoned the nine-rank system that had bred nepotism and corruption, drew the Confucian scholars back into power. Emperor Yang restored Confucian education and the examination system for officials, but in doing so lost the support of the nomads whom his father had courted. The capital was Daxing, the Chang'an of today's Xi'an, until Emperor Yang moved it in 605 to Luoyang, re-founded as a planned city.

Religion served legitimacy. Emperor Wen and his empress converted to Buddhism to justify imperial authority and the conquest of Chen; the emperor presented himself as a Cakravartin king who would defend the faith by force, and in 601 distributed relics of the Buddha to temples throughout China, an imitation of Ashoka of the Maurya Empire. The court also pursued a pro-Taoist policy, favouring the Northern Louguan school under Emperor Wen and the Southern Shangqing school under Emperor Yang. The 'Reign of Kaihuang', Emperor Wen's era name, was later counted among the high points of China's imperial history; Emperor Yang, who came to the throne after his father's death, possibly by murder, is remembered instead for costly wars and luxury at the peasantry's expense.

The Sui reunified China proper, closing the Northern and Southern dynasties era and the division that had lasted since the War of the Eight Princes, and in a short reign laid much of the groundwork for the Tang, which toppled them and then presided over a golden age. Often compared with the Qin, the Sui likewise unified the country after long division, carried out sweeping reforms and construction, and collapsed quickly. The Grand Canal was the lasting monument: extended from the Hangzhou region across the Yangtze to Yangzhou and north-west to Luoyang, it carried trade, people and cultural exchange for centuries.

Culturally the dynasty was a transition. Northern aristocrats became fascinated with everything the conquered south offered, and developments begun under the Sui were consolidated under the Tang. Buddhism was encouraged across the empire, and local Chinese schools flourished: Zhiyi founded the Tiantai school and completed the Great Treatise on Concentration and Insight, teaching 'Three Thousand Realms in a Single Moment of Life' as the essence of the Lotus Sutra. The Confucian Wang Tong briefly held office as Secretary of Shuzhou; his Explanation of the Mean was compiled soon after his death in 617. News of the reunification even reached the Byzantine Empire: the 7th-century historian Theophylact Simocatta gave a generally accurate account of Emperor Wen's conquest of Chen, placing it in the reign of Maurice.

The dynasty was undermined by ambitious wars and construction that overstretched its resources. Emperor Wen was famous for bankrupting the treasury with warfare and building, and under Emperor Yang heavy taxation and compulsory labour duties grew heavier still. Work on the Great Wall and the Grand Canal strained the economy and angered the conscripted workforce, and the four failed Goguryeo campaigns, ending in defeat by 614, left the country in ruins. Invasions by Turkic nomads and Emperor Yang's life of luxury at the peasants' expense cost him public support. In the dynasty's last years rebellion drew able-bodied men away from the farms; some deliberately broke their limbs to avoid conscription, calling it 'propitious paws' and 'fortunate feet', a practice Emperor Taizong of Tang was still trying to stamp out in 642.

Rebels soon controlled the government. Threatened by rebel groups, Emperor Yang went south and in 618 was assassinated by his Yuwen clan advisers, the minister Yuwen Huaji among them. In the north the aristocrat Li Yuan rose and ascended the throne as Emperor Gaozu of Tang. A brief civil war followed, but the Tang kept the Sui political system almost intact, so that the 37-year dynasty is remembered as the bridge between the age of division and the Tang golden age. Centuries later the Later Jin of the Five Dynasties still kept dukedoms for descendants of the Zhou, Sui and Tang royal houses.