佛祖統紀 35.6

35.6

元狩元年。初博望侯張騫自月氏還（西域國名）言臣在大夏時（音下國名）見卬竹杖蜀布。問安得此。國人曰。吾賈人市之身毒（即天竺音䖍篤）身毒在大夏東南可數千里。此其去蜀不遠。乃令騫因蜀犍為（犍音䖍今嘉州）發間使王然於等指之身毒（間諜之義。又間歲遣使。言不一）四歲餘皆閉昆明莫能通（為昆夷所閉）。

In the first year of Yuanshou, previously, Marquis of Bowang Zhang Qian returned from the Yuezhi (a state in the Western Regions) and stated: 'When your servant was in Daxia (name of a state), I saw bamboo canes from Qiong and cloth from Shu. I asked how they obtained these. The people of that state said: "Our merchants bought them in Shendu (which is Tianzhu)." Shendu lies several thousand li southeast of Daxia. This cannot be far from Shu.' Thereupon, [the Emperor] ordered Qian, by way of Qianwei in Shu (present-day Jiazhou), to dispatch secret envoys such as Wang Ranyu to head for Shendu (meaning undercover reconnaissance; also, envoys were sent in alternate years, accounts vary). For over four years, all were blocked by the Kunming and none could pass through (blocked by the Kunyi).