Reign of Emperor Xuanzong: the Kaiyuan and Tianbao eras

A grandson of Wu Zetian, Li Longji conspired with his aunt, Princess Taiping, in the coup of 710 that destroyed Empress Wei and restored his father Ruizong to the throne. On 31 August 712 Ruizong decreed his abdication in Li Longji’s favour, and on 8 September Li Longji took the throne. On 29 July 713 the young emperor struck down Taiping’s faction; the princess hid in a mountain temple for three days, and a few days later he ordered her to kill herself. On 22 December 713 he adopted the era name Kaiyuan. With chancellors such as Yao Chong, Song Jing and Zhang Yue, and later Zhang Jiuling, he gave the empire political stability and prosperity, and the Kaiyuan era is usually viewed as one of the golden ages of Chinese history, when literature, music, painting and sculpture flourished; in the early 740s the emperor summoned the poet Li Bai to court and gave him a post in the Hanlin Academy.

In the Tianbao era, which began in 742, the balance changed. The emperor, who in 745 made Yang Guifei his consort of the highest rank, left the government to the chancellor Li Linfu and, after Li’s death in 752, to her second cousin Yang Guozhong. Ever larger armies stood on the frontiers under military governors (jiedushi), some of them, like An Lushan, of non-Chinese origin; An Lushan commanded three frontier provinces in the north-east. In 751 the Tang suffered two defeats on distant frontiers — at Talas in Central Asia, where Gao Xianzhi was beaten by an Abbasid army, and in Yunnan, where Nanzhao destroyed an army sent against it. According to the Zizhi tongjian, when the eunuch Gao Lishi warned in 754 that the armies in Yunnan had been lost again and again and that the frontier generals held too many troops, the emperor told him to say no more — he would think it over.

An Lushan’s rebellion, which broke out in December 755, drove Xuanzong from Chang’an in July 756. At Mawei his guards killed Yang Guozhong and forced him to have Yang Guifei put to death, and on 12 August his son proclaimed himself emperor at Lingwu; Xuanzong accepted the title of retired emperor, returned to Chang’an in January 758 and died there in 762. His forty-four-year reign thus saw both the height of Tang power and the beginning of its long decline.