《资治通鉴·晋纪·晋纪三十八》
河西的胡人曹龙等人带领部众二万多人前来进犯蒲子，西河胡人张外向他投降，推举曹龙为大单于。
河西胡曹龙等拥部众二万人来入蒲子，张外降之，推龙为大单于。
Cao Long and others from the Hu people in Hexi led more than 20,000 of their tribe members to attack Pizi, and Zhang Wai, a Hu from Xi’an surrendered to him, and recommended Cao Long to be the Great Chanyu.