《汉书·传·西域传上》
后来贰师将军进击大宛，匈奴想截击汉军。但汉军兵力强盛，匈奴不敢抵挡，就派骑士藉楼兰的帮助，等候汉使走在后边的，截之不让通过。
后贰师军击大宛，匈奴欲遮之，贰师兵盛不敢当，即遣骑因楼兰候汉使后过者，欲绝勿通。
Later, the general of the 2nd army attacked Dawan, and the Huns wanted to intercept the Han army. However, the Han army was so powerful that the Huns dared not resist, so they sent cavalry with the help of Loulan to intercept the Han envoy who was walking behind and prevent them from passing through.