Hecang Fortress which also named as Square City is located 20 kilometers to the east of Yumenguan Pass as well as 60 kilometers away from Dunhuang City in the Gobi Desert. The fortress was constructed along the side of Shule River and hidden within the large Gobi Desert. As the fortress is very tiny in comparison with the huge desert, it is hard for you to discover the fortress unless you are close enough. This is the reason why the ancient people had built a quartermaster depot here.