《新唐书·列传·卷一百四十六》
宇文氏请求能入宗籍，诏赐李氏，改封为常乐公主。后来，文泰与西突厥交往，凡西域去朝贡的都要借道其国，均遭堵劫。
出细氈褐。西三百里度石碛至凌山，葱岭北原也，水东流，春夏山谷积雪。西北五百里至素叶水城，比国商胡杂居。
The Yuwen clan asked to be included in the imperial lineage, and they were granted the Li clan and renamed Princess Chang Le. Later, Wentai had dealings with the Western Turks, and every time someone from the Western Regions went to pay tribute, they had to pass through his country and were blocked and robbed.