公元840年，回鹘汗国因自然灾害侵袭、治集团内讧及黠戛斯（国古族名）的进攻等原因而崩溃，其部众大部分向西迁徙。
The Uighur Khanate collapsed in840 because of natural disasters , internal strife and attacks by the ancient jiegasi tribe . consequently , most of the Uighur migrated westward .
回鹘汗国