Sui and Tang dynasties

In 581 Yang Jian (杨坚), a Northern Zhou general who had become regent, forced the child emperor to abdicate and founded the Sui dynasty (隋朝). As Emperor Wen (隋文帝) he massed his troops on the Yangtze in 588; the following year his armies entered Jiankang and the last Chen emperor surrendered. Nearly three centuries of division were over.

The Sui rebuilt the state: a reorganised central administration that the Tang would inherit, an equal-field system meant to narrow the gap between rich and poor, a unified coinage, public granaries. In 582 Emperor Wen had a new capital, Daxing, built south-east of the ruins of Han Chang'an, and he opened a first canal linking it to the Yellow River. His son, Emperor Yang (隋炀帝), turned it in the early 7th century into a vast network, the Grand Canal (大运河). Centred on Luoyang, it linked Chang'an in the west, Jiangdu (today's Yangzhou) and Yuhang (today's Hangzhou) in the south, and the northern frontier near today's Beijing. Its first purpose was to carry grain to the capital and supply the armies; for centuries afterwards it carried goods and travellers between north and south. Millions of conscripted labourers dug it, at a heavy human cost. UNESCO added it to the World Heritage List in 2014.

These works, followed by disastrous campaigns against Goguryeo, one of the kingdoms of Korea, which ended in defeat in 614, exhausted the country. Revolts spread; in 618 Emperor Yang, who had taken refuge in Jiangdu, was killed by men of his own entourage. The Sui are often compared with the Qin: like them, they reunified China and reformed it deeply, then collapsed after only thirty-seven years.

Since the kingdom of Wei in the 3rd century, officials had been recruited by recommendation under the "nine-rank system" (九品中正制), and the great families had come to keep the best posts for themselves. The Sui set out to break this aristocratic hold and strengthen the emperor. In 587 Emperor Wen required every prefecture to send three candidates a year, and examinations appeared on the Confucian classics (明经) and on statecraft (秀才). Emperor Yang then created the examination for "presented scholars", the jinshi (进士), in 605 or 607 depending on the source. The imperial examinations (科举) were born under the Sui, but at first they changed little: only candidates recommended by senior officials could sit them.

The Tang made them a regular institution. From 622 almost any man could put himself forward. There were six examinations (cultivated talents, classics, jinshi, law, writing, arithmetic), but the jinshi, the hardest, gradually overshadowed the others: it tested the classics and history and, from the 730s, the composition of poems. Only one or two candidates in a hundred passed: just 6,585 jinshi degrees were awarded in three centuries of Tang rule. Wu Zetian, who needed support outside the great families, widened recruitment and created an examination presided over by the ruler in person. By the late Tang the jinshi degree had become a requirement for the highest offices.

With interruptions, the system lasted until it was abolished in 1905: some 1,300 years in which, in principle, learning rather than birth opened the doors of officialdom.

Li Yuan (李渊), an aristocrat and a cousin of Emperor Yang, rose in 617, took Chang'an and in 618 proclaimed the Tang dynasty (唐朝). His son Li Shimin (李世民) led the campaigns against its rivals. In 626, at the Xuanwu Gate, he ambushed and killed two of his brothers, one of them the crown prince; shortly afterwards his father abdicated in his favour. He reigned until 649 and is known to history by his temple name, Taizong (唐太宗).

Despite that bloody start, his reign, the Zhenguan era (贞观之治), became the model of good government that crown princes were expected to study. Taizong surrounded himself with capable ministers and put up with their criticism: he refused to send his adviser Wei Zheng away even for a day, since Wei's task was to point out his faults. In 630 his armies destroyed the Eastern Turkic Khaganate, and the Turks accepted him as their "Heavenly Khagan" (天可汗). The Tang then extended their reach as far as the Tarim Basin.

The capital took back the name Chang'an (长安). Laid out by the Sui, it formed a vast walled rectangle, gridded with straight avenues and walled wards, with two great markets. Along with Constantinople and Baghdad it was one of the largest cities in the world: before 755 it is estimated to have had between 800,000 and a million people inside its walls. A cosmopolitan city, it drew Sogdians, Persians, Japanese and Koreans; the West Market had a Persian bazaar, and the city had Zoroastrian temples and Christians of the Church of the East, who arrived around 635. The Tang's neighbours, above all Japan and Korea, adopted much of their institutions and culture.

Wu Zhao (武曌), better known as Wu Zetian (武则天), entered the palace as a concubine of Taizong. After his death she became a consort of his son and successor, Gaozong, who made her his empress in 655. When the emperor fell seriously ill, from 660, she governed in his place. On his death in 683 she kept power as empress dowager, pushing her two sons off the throne one after the other. On 16 October 690 she proclaimed her own dynasty, the Zhou (武周), and took the title of emperor (皇帝). She is the only woman in Chinese history whose reign in her own name is recognised.

Her reign had two faces. She relied on informers and ruthless laws, and had members of the Li imperial family and ministers of the old court eliminated. But she also widened recruitment by examination, to surround herself with officials of humbler origins, patronised Buddhism, literature and the arts, and fought Turkic and Tibetan incursions. She preferred Luoyang, the Eastern Capital, to Chang'an.

In 705 a coup overthrew her and restored the Tang; she died a few months later. Counting her years governing for Gaozong, her regency and her own reign, she had held the reins of the empire for some 45 years.

The monk Xuanzang (玄奘, 602–664) found the Buddhist texts translated into Chinese incomplete and contradictory, and wanted to seek out the originals in India. Since the court then banned travel abroad, he left Chang'an without permission in 629 (627 according to some early accounts). By way of the oases of Central Asia he crossed the mountains into India, and studied at the great monastery of Nalanda. He came home in 645, after sixteen years away, with 657 Sanskrit texts. Taizong received him with honour; Xuanzang turned down the posts he was offered and spent the rest of his life translating, at the head of a translation bureau. He dictated an account of his journey, the Great Tang Records on the Western Regions (大唐西域记), a valuable source on 7th-century India and Central Asia. Nine centuries later his journey became, heavily fictionalised, the novel Journey to the West (西游记).

Buddhism is also tied to a technique developed under the Tang: woodblock printing. In 1900 a Daoist monk at Dunhuang found a hoard of manuscripts in a walled-up cave of the Mogao complex; the printed scroll of the Diamond Sutra (金刚经) among them, bought in 1907 by the archaeologist Aurel Stein, is now in the British Library. Its colophon says that one Wang Jie had it made "for universal free distribution" on behalf of his parents, in 868. It is not the oldest print known, but it is the oldest printed book that bears a date.

Tang Buddhism then suffered a severe blow: in 845 Emperor Wuzong had monasteries closed on a massive scale, and Buddhism's influence declined afterwards.

Tradition regards the Tang as the greatest age of Chinese poetry, and two of its poets are among China's most famous. Li Bai (李白, c. 701–762) spent his childhood in Sichuan and travelled widely; his reputation earned him a summons to the court of Emperor Xuanzong, who in the end sent him away. He then formally became a Daoist. He wrote of friendship, nature, solitude and wine, and was nicknamed the "Immortal of Poetry" (诗仙). About a thousand of his poems survive. A legend has it that he drowned, drunk, reaching for the moon's reflection in the water.

Du Fu (杜甫, 712–770), his junior, whom he met in 744, sat the examinations twice without success and struggled to obtain a post. The An Lushan rebellion drove his family from their home; held by the rebels in Chang'an, he wrote "Spring View" (春望), whose first line is given below. He is called the "Sage of Poetry" (诗圣) or the "Poet-Historian" (诗史): his poems record war, exile and everyday life. Nearly 1,500 of his poems survive.

Li Bai's "Quiet Night Thought" (静夜思) is one of the poems Chinese schoolchildren learn by heart. Here is the text given in the anthology Three Hundred Tang Poems (18th century). Versions differ: the editions of Li Bai's complete works never have the word "bright" (明), and read "I look at the moonlight" (看月光) in the first line and "I gaze at the mountain moon" (望山月) in the third.

Under Emperor Xuanzong (唐玄宗, r. 712–756) the Tang reached their height. But to hold the frontiers the court relied on military governors, the jiedushi (节度使), who came to rival the central government. One of them, An Lushan (安禄山), a general of Sogdian and Turkic origin who had won the trust of the emperor and of his consort Yang Guifei (杨贵妃), commanded three northern garrisons, in effect the whole region north of the lower Yellow River. On 16 December 755 he rebelled, took Luoyang and proclaimed himself emperor of a Yan dynasty. In 756 Xuanzong fled towards Sichuan and Chang'an fell. On the way, at Mawei, his escort mutinied, killed the chancellor Yang Guozhong, the favourite's cousin, and demanded Yang Guifei's death: the emperor had to have her strangled, and then abdicated in favour of his son.

With Uyghur help the Tang recovered their capitals. An Lushan was murdered in 757, but the war did not end until February 763. It was the great turning point of the dynasty. The registered population fell from about 53 million people in 755 to 17 million in 764, although several historians point out that much of the gap reflects the collapse of the registers. The military governors became all but independent, the empire lost the Western Regions of Central Asia for good, and the economic centre shifted to Jiangnan, south of the Yangtze.

The dynasty lasted nearly another century and a half. In the 870s the rebellion of Huang Chao (黄巢), a salt smuggler who had repeatedly failed the examinations, devastated the country; in 881 he took Chang'an and made it the seat of his own dynasty. Zhu Wen (朱温), one of his former lieutenants who had gone over to the Tang, became master of the court: he forced it to leave Chang'an for Luoyang, had the emperor killed in 904 and in 907 deposed the last Tang ruler. The Five Dynasties and Ten Kingdoms period began; Chang'an never regained its rank.