Located in Dai County, Xinzhou City, Shanxi Province, Yanmenguan is one of the most important passes through the inner line of the Great Wall within the Hengshan Mountain Range. The site is renowned for its strategic importance and difficult to pass. Around 1,700 battles have taken place there since ancient times. Early in the Warring States Period (340 BC- 295 BC), King Wuling of Zhao first built the pass to defend against the Inner Asian nomads. It was reconstructed and moved to its current location in 1374. [Photo by Mi Xingang/China.org.cn]