怛罗斯战役
In 747, the hold of Tibet was loosened by the campaign of general Gao Xianzhi, who tried to re-open the direct communications between Central Asia and Kashmir. By 750, the Tibetans had lost almost all of their central Asian possessions to the Chinese. However, after Gao Xianzhi's defeat by the Arabs and Qarluqs at the Battle of Talas (751) and the subsequent civil war known as the An Lushan Rebellion (755), Chinese influence decreased rapidly and Tibetan influence resumed.