In 840, a civil strife broke out in the Huihu Khanate on the Mongolian Plateau. Julu Mohe, a rebel chief, invited his rival Qïrqïz and together with a force of 100,000 soldiers, they attacked the Huihu capital, killed the khaghan, and the Huihu Khanate north of the desert and even extending to the Western Regions was destroyed. Then, the thirteen clans close to the Khan’s headquarters supported Tegin Wujie as Khan, moved southward and submitted to the Tang Dynasty. The Huihu prime minister Sazhi supported Tegin Pang, the Khan’s nephew, and moved westward with fifteen clans, some of which were scattered halfway south and entered the Hexi Corridor through the Huamen Mountains, while the main force arrived in the east of the Tianshan Mountains hoping to survive and develop in the old territory of the Huihu Khanate. Subsequently, Tegin Pang established himself in Yanqi, known as Yabhu, and later, he claimed himself Khan in Anxi, occupying all the cities west of the desert. By now, in the eastern part of the Tianshan Mountains, there were not only the former officials of the old Huihu Khanate, but also the main force of the Huihu coming with the Tegin and some minor tent groups scattering here and there living on robbery.