It was a famous passage in ancient China. Legend has it that Hetian Nephrite was transported to the Central Plains from the Western Regions through the Yumen Pass. Since the Han-Wei period (206BC-265AD), the Yumen Pass has long been a strategic passage of the westernmost border leading to the Western Regions and also the inevitable passage of the famous Silk Road.

The Yumen Pass was also known as the Small Fangpan City, where the city walls still remain. It is square-shaped and has a gate to the west, although the northern wall gate has been sealed off. The fortress was built on yellow puddle boards, with walls 9.7 meters high. Surrounded by barracks, emplacements and pagodas, the fortress is 24 meters wide form east to west and 26 meters long from south to north, covering an area of over 630 square meters. Also discovered at the site was a large number of bamboo slips from the Han Dynasty.

The Big Fangpan City, located about 20 kilometers northwest of the Small Fangpan City,  served as the quartermaster depot for troops stationed on the Chinese west border during the Han-Wei period. The oblong city was built using rammed earth on wooden boards and measures 132 meters from east to west and 17 meters from south to north. Remaining parts of the wall reach a maximum of 6.7 meters. The city was divided into an inner and outer city, although walls from the former city have all been destroyed. Wall ruins and traces of constructions at the four corners of the inner city still exist.

The section of Great Wall near the Yumen Pass was built with layers of sand gravels and reeds. Well-preserved firewood was piled up near the beacon towers. This is the best-preserved section of the Great Wall built in the Han Dynasty in China. Excavations at the Maquanwan Beacon Tower Site produced orderly foundations and a large number of cultural relics -- the most important being the bamboo slips from the Western Han Dynasty.