Yanmen, or Wild Goose Pass, is situated in the northwest corner of Daixian County. The undulating Great Wall in north Daixian County looks like a dragon lying atop mountains. This has traditionally been considered critical military position due to its geographical location. Yanmen Pass was built in the early Tang Dynasty (618-907) as a garrison for troops. A legend has it that the mountains were so high here that even wild geese couldn't fly over them. The pass was the only way for them to fly through. Hence the name of Wild Goose Pass.

The peaks on both sides of the Yanmen Pass are high cliffs, forming a natural gate. Yanmen Pass was seen as impossible to be attacked, even if there was only one soldier at the pass. Above the pass is a horizontal board with three inscribed Chinese characters: Yan- Pass. On either side is an antithetical couplet inscribed with the characters: "the foremost critical pass on the earth; holding a prominent position in the hearts of the people."