As early as Lu Chunqiu, there was a record that "there are nine blocks in the world, and one of them is a hook", which is the hook mountain in Luliang Mountain where Yanmenguan is located. It is said that "Lulong, flying fox and Yanmen are the first dangers in the world".
As an ancient military fortress, Yanmenguan has a long history, dangerous terrain, complete system, important position and frequent wars, ranking first in China's famous pass.
Extended data:
geographical position
Yanmenguan reaches Pingxingguan, Zijingguan and Daomaguan in the east, reaching the secluded rock and connecting the vast sea; West to Ning Wuguan Xuankou, Piantouguan to the Yellow River. Hengshan Mountain winds along the northern boundary of Daixian County at the top of the Inner Great Wall, connecting Yanmen Mountain, Mantou Mountain and Caoduo Mountain.
It borders Yanbei Plateau in the north and Ding Xin Basin in the south. Yanmenguan is located on Gouzhuling in the north of Daizhou ancient city, on Yanmen Mountain, about 20 kilometers north of Daixian in the north of Shanxi Province. The "First Pass of Nine Tournaments" stands on the mountain and stands on the hook, which is one of the main central passages for geese to return from south to north.
References:
Baidu Encyclopedia-Yanmenguan