The seventh century marks the beginning of the medieval period of Chinese history. This was the age in which Chinese culture reached its most cosmopolitan and sophisticated peak, a time of experimentation in literature, art, music and agriculture, and one which unified seemingly incompatible elements.

Having changed his name to Gao Zu, Li Yuan consolidated his new Tang dynasty by spending the rest of his eight-year reign getting rid of all his rivals. Under his son Tai Zong , Tang China expanded: the Turks were crushed, the Tibetans brought to heel and relations established with Byzantium. China kept open house for traders and travellers of all races and creeds, who settled in the mercantile cities of Yangzhou and Guangzhou, bringing with them their religions, especially Islam , and influencing the arts, cookery, fashion and entertainment. China's goods flowed out to India, Persia, the Near East and many other countries, and her language and religion were adopted by Japan and Korea. At home, Buddhism remained the all-pervading foreign influence, with Chinese pilgrims travelling widely in India. The best known of these, Xuan Zang , set off in 629 and returned after sixteen years in India with a mass of Buddhist sutras, adding greatly to China's storehouse of knowledge.

Xi'an's population swelled to over a million and it became one of the world's great cultural centres, heart of a centralized and powerful state. A decade after Tai Zong's death in 649, his short-lived son Gao Zong and China's only empress, Wu Zetian , had expanded the Tang empire's direct influence from Korea to Iran, and south into Vietnam. Wu Zetian was a great patron of Buddhism, commissioning the famous Longmen carvings outside Luoyang, and, though widely unpopular, she created a civil service selected on merit rather than birth. Her successor, Xuan Zong , began well in 712, but his later infatuation with the beautiful concubine Yang Guifei led to the collapse of his rule in 756, his flight to Sichuan and Yang's ignominious death at the hands of his mutineering army. Xuan Zong's son, Su Zong , enlisted the help of Tibetan and Uigur forces and recaptured Xi'an from the rebels; but though the court was re-established, it had lost its authority, and real power was once again shifting to the provinces.

The following two hundred years saw the country split into regional political and military alliances. From 907 to 960 Five Dynasties succeeded each other, all too short-lived to be effective. China's northern defences were permanently weakened, while her economic dependence on the south increased and the dispersal of power brought sweeping social changes. The traditional elite whose fortunes were tied to the dynasty gave way to a military and merchant class who bought land to acquire status, plus a professional ruling class selected by examination. In the south the Ten Kingdoms (some existing side by side) managed to retain what was left of the Tang civilization, their greater stability and economic prosperity sustaining a relatively high cultural level.

Finally, in 960, a disaffected army in the north put a successful general, Song Tai Zu , on the throne. His new ruling house, known as the Northern Song , made its capital at Kaifeng in the Yellow River basin, well-placed at the head of the Grand Canal for transport to supply its million people with grain from the south. By skilled politicking rather than military might the new dynasty consolidated its authority over surrounding petty kingdoms and re-established civilian primacy. But in 1115, northern China was occupied by the Jin , who pushed the imperial court south to Hangzhou where, guarded by the Yangzi River, their culture continued to flourish from 1126 as the Southern Song . Developments during their 150-year dynasty included gunpowder, the magnetic compass, fine porcelain and moveable type printing. But the Song preoccupation with art and sophistication saw their military might decline and led to them underrating their agressive "barbarian" neighbours, whose own expansionist policies culminated in the thirteenth-century Mongol Invasion.