《水经注·卷三》
老城南对长河，北依连山。秦始皇驱逐了匈奴，傍着河水东岸修筑保垒，与阴山连成一线，成为河上的要塞。
其城南面长河，北背连山，秦始皇逐匈奴，并河以东，属之阴山，筑亭障为河上塞。
The old city faces the Long River in the south and leans on the Lian Mountain in the north. Qin Shihuang drove out the Huns, built a fortress on the east bank of the river, and connected it with Yinshan Mountain, becoming a fortress on the river.