《史记·三十世家·赵世家》
武灵王二十年，武灵王攻占中山国土地，到达宁葭；往西攻占胡人土地，到达榆中。
二十年，王略中山地，至宁葭。西略胡地，至榆中。
In the twentieth year of King Wuling, King Wuling attacked the Zhongshan State and reached Ningjia; westward, he reached Yuzhong after attacking the Hu land.