In the early 13th century, Genghis Khan, leader of the Mongols, established the Mongol Khanate in north China. In 1247 Sagya Pandit Gonggar Gyamcan, religious leader of Tibet, met the Mongol Prince Gotan at Liangzhou (present-day Wuwei of Gansu, China) and decided on terms for Tibetan submission to the Mongols, including presentation of map and census books, payment of tributes, and the acceptance of rule by appointed officials.
The Tibetan work Sagya Genealogy written in 1629 includes Sagya Pandit's letter to the religious and secular leaders in the various parts of Tibet that they must pledge allegiance to the Mongols and accept the regional administrative system prescribed for Tibet. The regime of the Mongol Khanate changed its title to Yuan in 1271 and unified the whole of China in 1279, establishing a central government, which, following the Han (206 BC-220) and Tang dynasties, achieved great unification of various regions and races within the domain of China. Tibet became an administrative region directly under the administration of the central government of China's Yuan Dynasty.
The Yuan emperor established the Xuanzheng Yuan or Ministry for the Spread of Governance to directly handle important military and political affairs of the Tibet region. Choice of its members lay with the emperor and its reports were submitted directly to the monarch. Yuanshi, the chief minister having real authority in the Xuanzheng Yuan, was a post generally held concurrently by the right-hand prime minister of the central government who was in charge of the whole nation's governmental affairs.
In the Tibetan region, local military and administrative organs were set up under the name of the High Pacification Commissioner's Office, which was under the Xuanzheng Yuan. Under the jurisdiction of this office were 13 wanhu offices (myriarchies each in command of 10,000 households) and more qianhu offices (chiliarchies each in command of 1,000 households) handling civil administration. The names of these organizations and official posts were decided by the central government of the Yuan Dynasty. It also had troops stationed in Tibet. A royal prince and his descendents were stationed on the eastern border of Tibet at the head of an army. When Tibet was enmeshed in trouble, the prince could enter the area from nearby garrison to perform his duty of guarding the security of the border region. In 1290, when the head of a wanhu office rose in rebellion, the central government of the Yuan Dynasty dispatched the prince into Tibet at the head of his army to put it down.
The central government of the Yuan Dynasty sent officials into Tibet to set up post stations, whose size varied according to the local population, topography and resources. These post stations were linked up in a communication line extending from Tibet up to Dadu (present-day Beijing).
The central government of the Yuan Dynasty also dispatched officials into Tibet to conduct censuses, establish the number of corvee laborers in areas under various wanhu offices and decide the number of corvee laborers, provisions and animal transport the areas along the post route had to supply. Such censuses were conducted three times in Tibet, in 1268, 1287 and 1334. The Tibetan work History From the Han and Tibetan Sources records them in detail.