The Tang Empire, aided by Muslims in…

The Tang Empire, aided by Muslims in the west and the Bai kingdom of Nanzhao in the south, has fought intermittently with the Tibetan Empire for control of areas in Inner and Central Asia, which has at times been settled with marriage alliances.

There had been a long string of conflicts with Tibet over territories in the Tarim Basin between 670–692, and in 763, the Tibetans had even captured Chang'an for fifteen days amid the An Shi Rebellion.

Hostilities continue until 821, when a formal peace treaty is finally signed between the Tang Dynasty and the Tibetan Empire.

A bilingual inscription on a stone pillar outside the Jokhang temple in Lhasa records the terms of this treaty, including the borders between the two countries.