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.

Mural commemorating victory of General Zhang Yichao over the Tibetan Empire in 848 ( Mogao cave 156, late Tang dynasty )