Introduction to Pianguan: Pianguan is located in Pianguan County, Shanxi Province. Together with Ningwuguan and Yanmenguan, it is known as the "Three Outer Passes" of the Inner Great Wall. To the east is the remaining range of Hengshan Mountain, and to the west is It is close to the Yellow River, facing Inner Mongolia and Datong to the north, and connected to Ningwuguan to the south. This place has been a battleground for military strategists since ancient times. Because the walls on both sides of the original Guan City were tilted east and west, shaped like the side of a human head, it was called Pianguan.