《水经注·卷二十七》
通关势山高百余丈，山上有一座匈奴城，周围五里，环城有三道深沟。汉高祖北定三秦后，萧何据守汉中，他想往北修一条通往关中的道路，因而名为通关势。
山高百余丈，上有匈奴城，方五里，濬堑三重，高祖北定三秦，萧何守汉中，欲修北道通关中，故名为通关势。
Tongguan Shi is over a hundred zhang tall. There is a Xiongnu City on the mountain, with a perimeter of five li and three deep ditches around the city. After Han Gaozu pacified the Three Qins in the north, Xiao He defended Hanzhong. He wanted to build a road leading to Guanzhong in the north, so it was named Tongguan Shi.