《汉书·传·西域传上》
西夜人与胡人不同，与羌、氐等游牧民族相似，随牲畜逐水草而居。
西夜与胡异，其种类羌氐行国，随畜逐水草往来。
The people of Xiyue differ from the Hu people, but are similar to the Qiang and Di peoples as they are nomadic herders who follow their herds to find water and grass.