After the Uighur Khanate in the northern desert fell down, part of those Uighur captives were settled down in the states of Liang and Gan on their way of westward migration by the Tibetan conquerors. In the first year of the imperial title of Qianfu, this group of Uighur residents was defeated by the allies of the Shangbibi Group of Tibet, the Tuyuhun kingdom and the like. After that, the group continuously expanded westwards and captured the state of Gua in the 3rd year of the imperial title of Qianfu. In October in the 4th year of the imperial title of Qianfu, Zhang Huaishen, military governor of the Guiyi army, started an eastward military expedition after defeating the Uighur’s invasion in the state of Sha and recaptured the state at one stroke. After recapturing the state of Sha, Zhang sent a diplomatic mission to Changan, hoping to be appointed as military governorship of the Tang Dynasty. Under the epical circumstances of attempting to keep the territory west of the Huanghe River, the Tang court promoted Zhang Huaishen to a probationary major. However, this attempt ended in failure which was to make great effects on the development of political situation in this area after then.

the Tang Dynasty’s territory west of the Huanghe River; the Guiyi army; the state of Gua; Uighur; Dunhuang documents