A series of kings ruled Tibet from the 7th to the 11th century. At times, Tibetan rule may have extended as far south as Bengal and as far north as Mongolia.[citation needed] Tibet appeared in an ancient Chinese historical text where it is referred to as fa. The first incident from recorded Tibetan history which is confirmed externally occurred when King Namri Lontsen sent an ambassador to the Chinese court in the early 7th century.[16] However general, the history of Tibet begins with the rule of Namri Songzen, who first attempts to unify Tibet. His son Songtsän Gampo (604–649 AD) united parts of the Yarlung River Valley and ruled Tibet as a kingdom. In 640 he married Princess Wencheng, the niece of the powerful Chinese emperor Emperor Taizong of Tang China. Tibetan forces conquered the Tuyuhun Kingdom of modern Qinghai and Gansu to the northeast between 663 and 672 AD. Tibet also dominated the Tarim Basin and adjoining regions (now called Xinjiang), including the city of Kashgar, from 670 to 692 AD, when they were defeated by Chinese forces, and then again from 766 to the 800s. The Tibetans were allied with the Arabs and eastern Turks. In 747, Tibet's hold over Central Asia was weakened by the campaign of general Gao Xianzhi, who re-opened 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 river (751), Chinese influence decreased rapidly and Tibetan influence resumed. Tibet conquered large sections of northern India and even briefly took control of the Chinese capital Chang'an in 763 during the chaos of the An Shi Rebellion.[17] There was a stone pillar, the Lhasa Shöl rdo-rings, in the ancient village of Shöl in front of the Potala in Lhasa, dating to c. 764 AD during the reign of Trisong Detsen. It also contains an account of the brief capture of Chang'an, the Chinese capital, in 763 AD, during the reign of Emperor Daizong.