Xiao Pass, Guyuan, Ningxia 宁夏固原萧关
Xiao Pass lay in the Jing River valley southeast of Guyuan, Ningxia, guarding the Xiaoguan Road that ran north from the Guanzhong plain to the steppe – the northern gateway of the Guanzhong. Under Emperor Wen of Han, Xiongnu horsemen broke through it and their beacon fires were seen close to Chang’an. The site shifted over the dynasties and its exact location is disputed; Wang Wei’s line “At Xiao Pass I met a mounted scout” refers to this place.