《汉书·传·西南夷两粤朝鲜传》
夜郎靠近胖柯江，江宽百余步，可行船，南粤人用财物使夜郎归附，南粤的影响，西面直达桐师，但是，还是不能够像对待臣属那样使唤夜郎。
夜郎者，临牂柯江，江广百余步，足以行船。南粤以财物役属夜郎，西至桐师，然亦不能臣使也。
Yelang was not far from the Pankou River, a river a hundred or more steps wide that could be used to sail boats. The people of Nanyue had used money and gifts to make Yelang their vassal. The influence of Nanyue extended as far as Tongshi in the west, but they had still to establish direct control over Yelang.