Nanzhao

Zhuge Liang's achievement only held until shortly after his death, when in 264 Wei conquered Shu. The annexed parts of Yunnan broke up into mini-states while the western tribes threw off suzerainty and regained their full independence. When Wei reunited the empire by defeating Wu in 2B0 it did not try to regain control of Shu's Yunnan territory. This new Jin Dynasty fell in 316 and until Sui reunification in 581 China was split into several short-lived northern and southern realms. None were strong enough to assert claims over any part of Yunnan. By the time the Tang Dynasty, succeeding the Sui in 618, felt powerful enough to try, Yunnan had under-gone important changes and was ready to resist any attempt to subjugate it.

The centre of power inYunnan had shifted from Kunming to Dali, 400 km west. The Tang emperors sought to pacify their frontiers by encouraging the political consolidation of border states , having them acknowledge Chinese suzerainty and themselves protect the area. By this time six small states, or zhao, had established themselves in the west These zhao acknowledged Tang suzerainty in 647. The most important one was the southern one, centred around modern Weishan, called Nanzhao.

In 718, at the peak of Tang power, Nanzhao's King Piluoge unified the six zhao. Twenty years later he marched north and subdued Tibetan and Yi tribes that had given Tang China trouble in southwest Sichuan. The court was pleased at its vassal's success.

But relations soon deteriorated. Piluoge's successor Geluofeng was insulted on a state visit to a Tang prince, failed to have his grievance addressed by a court distracted by the Yang Guifei affair (the emperor's mistress), and broke off Nanzhao's fealty to the Tang court. The latter's reaction was to dispatch a huge punitive expedition against the Nanzhao capital Dali. But Nanzhao defenders annihilated this army at Xiaguan in 751, putting 60,000 Tang soldiers to death. Three years later an avenging army set out from Chang'an and met the same fate.

King Geluofeng discussing state affairs with his courtiers

Then China suffered the throes of the An Lushan Rebellion, which broke out in 755 and lasted ten years, leaving the empire a shadow of its former self. Nanxhao took advantage and seized portions of Sichuan and for the next hundred years periodically waged war, sometimes in alliance with Tibet, against Tang China. Nanzhao in this period also occupied northern Burma and pushed east and south to Guangxi and Vietnam.

But by 879 the kingdom was too weak to carry out expansion. Its invasion of Sichuan was easily repulsed and It suffered a disastrous defeat in Vietnam the following year. Though the Tang dynasty in accelerated decline, Nanzhao was in no position to gain at the empire's demise. The very different disease of Burma made Nanzhao's stay there short-lived, while their conquest of Han-populated territory created new problems for the nun-Han ruling class tribals, who could not successfully assimilate their new subjects into the national polity.

Nanzhao's territory, which extended into Guizhou and Hunan, began to contract just as the Tang Dynasty began crumbling. In 902, five years prior to the end of the dynasty, the ruling family of Nanzhao was assassinated and the throne usurped by one of the state's satraps. Internecine fighting continued until ended by a Bai official's coup in 937. The new Kingdom of Dali lasted more than three centuries. It was not as large as Nanxhao, for it allowed the further flung provinces to secede and in reality had direct control only over the area which today comprises Dali Prefecture.

Nevertheless, it enjoyed a peaceful existence. The first Sung emperor, mindful of the Tang difficulties with the people of the southwest, declined trying to add Yunnan to his domain. Instead the Song policy was to do nothing to interfere with trade, for Yunnan was a valuable source of horses for the Song armies in their endless battles with mounted invaders from the north. Alter the withdrawal of Nanahao from the Upper Irrawaddi plains the new state of Burma did not try to expand east into Yunnan. Nor did Tibet ever revert to its aggressive policies of the early Tang centuries, So the Kingdom of Dali had no external enemies and no motive to keep a strong standing army of its own. When faced with the sudden need for one, in 1253, Dali was unprepared.