The prefecture (zhou 州) of Xizhou 西州 (Türkic name Turpan or Turfan) was one of the three prefectures (zhou 州) the Tang empire 唐 (618-907) set up in the Western Territories 西域 (the others were Tingzhou 庭州 and Yizhou 伊州). Xizhou included the districts (xian 縣) of Gaochang 高昌, Liuzhong 柳中, Jiaohe 交河, Puchang 蒲昌 and Tianshan 天山. During the mid-8th century the area was for a short time administered as commandery (jun 郡) of Jiaohe.
The seat of the prefecture, Gaochang (from 762 on called Qianting 前庭), was located in the place of modern Karakočo 哈拉和卓 (also writen 喀拉和卓), Xinjiang (near Turfan 吐魯番), and is part of the Turfan Basin. The first name of the prefecture was Xichang 西昌, but it was soon renamed Xizhou. The region had formerly been part of the kingdom of Gaochang whose dynasty was defeated by the Tang armies in 640. Jiaohe (Gaochang) was the first seat of the Protectorate of the Pacified West (Anxi duhufu 安西都護府) before it was transferred to Qiuci 龜茲 in 658. On that occasion the area command (dudufu 都督府) of Xizhou was set up.
In 714, a military garrison was set up in Tianshan, with a strength of 5,000 men. The administration of the region was transformed into the commandery of Jiaohe in 742, but in 758 the prefecture of Xizhou was revived. Xizhou was occupied by the Tibetans in 791 and in 866 by the Uyghurs 回鶻. The Uyghur khan Pu-gu-jun 僕固俊 declared his submission to the Tang court, and Yizhou was put under the administration of the military commissioner (jiedushi 節度使) of Guiyi 歸義 in Shazhou 沙州 (Dunhuang 敦煌).
The region was during that time also called Kočo (Chinese form Hezhuo 和卓 or Huozhou 火州) or "protectorate (duhu 都護) of Yi" 亦. Under the Mongols, the region was called the prefecture of Huozhou 火州 (a name derived from the name Kočo or Karakočo) and was administered by the garrison of Beš Baliq 別失八里.
The vicinity to the westernmost regular prefectures of the Tang empire resulted in a relatively good infrastructure of the region. In the 9th century there was a mixed population in Xizhou, consisting of Chinese, Uyghurs and other natives. The inhabitants produced grain, grapes and fabric. In the desert climate, a lot of administrative documents from the Tang period have survived.