《汉书·传·李广苏建传》
东路稍微迂回绕远，而大部队行经水草稀少的地方，其势不能聚集行进。
东道少回远，大军行，水草少，其势不屯行。
The east side was a slightly longer route, and the main force had to pass through areas with little grass and water, making it difficult to advance.