Gukou of Baoxie Road in Hanzhong is the most dangerous pass of Baoxie Road, with steep cliffs and fast-flowing water, so it is difficult to set up plank roads. During the Yongping period of the Eastern Han Dynasty, Emperor Hanming ordered a tunnel to be dug in the most dangerous place, which lasted for six years. It was called "Shimen" in ancient times. After the Shimen Road was broken, the secretariat sheep in Liang and Qin Dynasties in the Northern Wei Dynasty rebuilt the praise and oblique road. "Shimen Ming" was made to commemorate this event, and it is a famous cliff stone carving.