Briefly answer the source of settlers in the western regions of the Tang Dynasty.

The source of immigrants from the western regions in Tang Dynasty was mainly garrison soldiers.

During the prosperous Tang Dynasty, a prosperous country with a vast territory and unprecedented unity was formed. In order to defend the frontier, we must defend the frontier fortress. If the army's food is shipped from the central plains, it will be difficult to last. So Emperor Taizong decided to open up wasteland in Daxing, develop the western regions, solve the food supply of the army on the spot, and open up wasteland to defend the border. "Open the military government to keep the important place and set up fields because of the gap." "Make good farmers officials and adjutants." The western reclamation has developed rapidly. "After Zhenguan Kaiyuan, it started from Gaochang, Qiuci, Yanqi and Xiaobao Road in the west, and went to Xue Yantuo's hometown in the north. Dozens of States were heavily guarded and cultivated."

The development of the western regions in the Tang Dynasty was from east to west and from south to north, and the construction of wasteland base was also carried out in accordance with this law. With the gradual advancement of the influence of the Tang Dynasty in the western regions, especially after the establishment of "Anxi Four Towns", "Ding Nan was transferred to Shandong (referring to the east of Huashan Mountain in Shaanxi Province) as a garrison soldier at the age of 20, taking silk as military assets, reclaiming land for grain, herding sheep and sending horses, with an army of 10,000, a small army of 1,000, and Wan Li stationed in succession". According to the rough statistics of historical records, there were 20 huts in Qiuci (now Kuqa), 7 huts in Shule (now Kashi), 7 huts in Yanqi, 20 huts in Duhu (now Jimsar) in Beiting, 1 huts in Yizhou (now Hami) and/kl in Xizhou (now Turpan). According to historical records, "there are soldiers in Xizhou Town, and every 50 hectares is a village." One hectare is 100 mu, and one tun is 5 thousand mu. Due to the need of irrigation agriculture, Anxi Duhu House has set up a special institution "Taotuo Institute" to study water conservancy. From Emperor Taizong to Emperor Xuanzong of the Tang Dynasty, there were 44,000 troops stationed in the Western Regions at ordinary times, with 7,700 horses and rations of167,000 stone. The number of soldiers has reached more than100000, so the food supply of so many horses mainly depends on reclamation.