Yet, Bovingdon notes that both Uygur and Chinese narratives do not accord with the historical facts and developments, which are complex and interwoven, noting that the Han Dynasty (206 BC – 220 AD) established military colonies (tuntian) and commanderies to control Xinjiang from 120 BC, while the Tang dynasty (618–907) also controlled much of Xinjiang until the An Lushan rebellion. In the 9th century, after the fall of the Uyghur Khanate, the Uyghurs migrated to Xinjiang from the area encompassed by Mongolia, Inner Mongolia, and Siberia, having originated from the 'Mongolian core lands of the Orkhon river valley'. The name "Uyghur" originally was associated with a Buddhist people in the Tarim Basin in the 9th century, but completely disappeared by the 15th century, until it was revived by the Soviet Union in the 20th century.