《资治通鉴·宋纪·宋纪三》
刘等人一再请求，拓跋焘最后只好允许分出三万多帐落的牧民迁移到河西。向西行进到白盐池，敕勒部的牧民都惊骇不已，说： 朝廷把我们圈到河西，是要杀我们呀！ 
絜等固请不已，乃听分徙三万馀落于河西，西至白盐池。敕勒皆惊骇，曰： 圈我于河西，欲杀我也！ 
Liu and the others repeatedly asked, so Tuoba Tao finally allowed more than 30,000 tents of herdsmen to migrate to Hexi. Going westward to Baiyantan, the herdsmen of the Chele tribe were terrified, saying: The imperial court sent us to Hexi to kill us!