Tianbao War: Nanzhao destroys the Tang armies

Nanzhao had arisen in the 730s, when Piluoge, with Tang support, united the Six Zhao of the Erhai region. According to the Zizhi tongjian, Zhang Qiantuo, the Tang governor of Yunnan commandery, abused the wives of the Nanzhao king when they passed through his city, demanded gifts, had Geluofeng insulted when he refused and secretly denounced him to the court; in 750 Geluofeng rose, took Yunnan, killed Zhang and seized thirty-two prefectures of the local peoples. In the fourth lunar month of 751 (30 April – 29 May) Xianyu Zhongtong, military governor of Jiannan in Sichuan, marched against him with 80,000 men (60,000 in the Old Book of Tang). Geluofeng offered to apologise and return his captives, warning that a great Tibetan army stood at his border and that if refused he would submit to Tibet. Xianyu imprisoned the envoys, advanced to the Xi’er River, which flows out of Lake Erhai at modern Xiaguan, and was routed; 60,000 soldiers died and he barely escaped alone, while Yang Guozhong, who had secured his appointment and became chancellor the following year, concealed the defeat.

Geluofeng heaped up the Tang dead in a victory mound and submitted to Tibet, which styled him zanpu zhong, ‘younger brother of the btsanpo’, and ‘Eastern Emperor’ and gave him a gold seal. The Tang raised new troops by force: men dreaded the malarial south, and Yang Guozhong had censors seize them and send them to the army in cangues. In the sixth lunar month of 754 (25 June – 23 July) Li Mi led 70,000 men against Nanzhao (100,000 in some modern accounts). According to the Zizhi tongjian, Geluofeng drew them deep into his country, to his capital Taihe, and would not give battle; when their supplies ran out, seven or eight in ten died of disease and hunger, and as they withdrew the whole army was destroyed. The Tang histories say that Li Mi was captured; according to another tradition he threw himself into a river. In all, says the Zizhi tongjian, nearly 200,000 men perished in these campaigns, and no one dared to tell the emperor.

Nanzhao went on to take the rest of Yunnan and to raid Sichuan, and remained Tibet’s ally until 794, when it returned to the Tang. In 766 Geluofeng set up a stele at Taihe, which still stands, recounting the war and its causes; the Zizhi tongjian quotes him as saying that should his descendants return to the Tang, they should show it to the Tang envoys ‘so that they know my rebellion was not from my heart’. In Dali a tomb of the Tang soldiers who fell in the Tianbao war, known as the ‘tomb of ten thousand men’, is still shown.