Tubo is the ancestor of Tibetans and was originally a branch of Xiqiang. At the end of the 6th century, its core tribe, Sibuye, rose in the Yalong River area on the south bank of the Yarlung Zangbo River, unifying the Qiang people in the Pamirs. When Songzan Ganbu, he expanded his territory to Heyuan, joined forces with the Tang Dynasty, * * * eliminated Tuyuhun, and carved it up for himself. The relationship between Gaelic family and Tang Dynasty deteriorated. Since the first year of Longshuo (66 1), they began to compete fiercely with the Tang Dynasty for the Western Regions. In the 14th year of Tianbao (755), the Anshi Rebellion broke out and captured Longyou and Hexi Erdao, cutting off the contact between the Tang Dynasty and the garrison in the western regions. In the sixth year of Zhenyuan (790), the Northern Court was captured, and Xizhou was soon captured. In the third year of Zhiyuan (808), it captured Anxi, the last stronghold of the Tang Dynasty in the western regions, that is, Qiuci, and completed the conquest of Li region (that is, the western regions in China's historical materials). Naturally, a large number of Tubo soldiers and civilians migrated to the north and south of Tianshan Mountain and joined the ranks of Xinjiang ethnic family. In addition to the royal family, Tubo has other giants, such as Niang's, Wei's, Lang's and Wu's. They not only have hereditary fiefs, but also hereditary courtiers. The courtiers have their own fiefs, courtiers and sects, which are layered like pagodas. This is obviously a feudal Lord system. With the expansion of Tubo forces to all parts of the country, its officials and soldiers are stationed everywhere, which brings new content to this traditional system. Officials have their own paid fields, and agricultural envoys are equivalent to the Tang Dynasty. After Tubo took over the western territory of the Tang Dynasty, he inherited the Tang system, set up this official, and led the army to settle the field. Grass-roots producers can be roughly divided into two categories, one is freemen, that is, ordinary farmers, who have no hereditary privileges. There are also differences in fields and acres in Tubo bamboo slips. Field refers to cooked fields, land refers to wasteland, and domestic slaves refer to serfs with strong personal attachment. Tubo widely uses domestic slaves, almost all of which are occupied by conquered nations or prisoners of war. For example, the Han people or the city-state Tubo is a nation that mainly engages in animal husbandry and concurrently engages in agriculture. Animal husbandry is very developed, and Tibetan animal husbandry is very distinctive, especially yaks and single-mountain camels. Yaks are hardy, hard-working and good at walking mountain roads. It is usually used as a pack animal. Its skin is thick and can be used to make armor. One mountain camel is good at galloping, and there are also other places. Tubo horses have excellent varieties and a large number, so their cavalry are invincible.