《资治通鉴·齐纪·齐纪三》
当时柔然汗国的百姓认为郁久闾那盖得到了上天的帮助，于是，就杀死了郁久闾豆仑，立郁久闾那盖为可汗，称他为候其伏代库者可汗，改年号为太安。
国人以那盖为得天助，乃杀伏名敦而立那盖，号候其伏代库者可汗，改元大安。
At that time, the people of the Rouran Khaganate believed that Yugu Yulü Nagai had been blessed by the heavens, and thus, killed Yugu Yulü Doulin and installed Yugu Yulü Nagai as Khagan, giving him the title Houqifu代库者Khagan, and changed the era name to Tai’an.