The keeper of the pass,
尹喜, is said to have seen a purple haze coming from the east before Laozi arrived, the source of
紫气东来, and to have asked him to write down his teaching, the 《
道德经》.
孟尝君 escaped Qin through the same pass when a follower crowed like a cock to get the gate opened, the story of
鸡鸣狗盗.
