Beiting Protectorate

[5] In 755 the An Lushan Rebellion occurred and the Tang dynasty withdrew 200,000 soldiers from the Western Regions to protect the capital.

[6] In 764 the Tibetan Empire invaded the Hexi Corridor and conquered Liang Prefecture,[7] cutting off the Anxi and Beiting from the Tang dynasty.

However the Anxi and Beiting protectorates were left relatively unmolested under the leadership of Guo Xin and Li Yuanzhong.

[8] In 780 Li Yuanzhong was officially made protectorate general of Beiting after sending secret messages to Emperor Dezong of Tang.

[10] In the immediate aftermath of the Tibetan conquest of Xi Prefecture, it was taken by the Uyghur Khaganate, after which the area became the border between the two empires.