Aspects of this topic are discussed in the following places at Britannica.
...had extended westward even beyond the limits of present-day Xinjiang. To the north, in the region of the Orhon River and to the north of the Ordos (Mu Us) Desert, the Tang armies defeated the Xueyantou (Syr Tardush), former vassals of the eastern Turks, who became Tang vassals in 646. The Tuyuhun in the region around Koko Nor caused considerable trouble in the early 630s. Taizong invaded...
We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.
Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.