Han Xiongnu Wars : Hangu Pass

Hangu Pass or Hanguguan is a pass separating the upper Yellow River and Wei valleys—the cradle of Chinese civilization and seat of its longtime capital Xi'an—from the fertile North China Plain. It lies on the south bank of the Yellow River just east of its eastward bend out of the Ordos Loop at Tongguan in Shaanxi. It was the site of many battles during the Warring States and early imperial eras, when it was the chokepoint shielding Qin, Guanzhong, or Luoyang from outside attack. Today, the Hangu Pass forms part of the area of Lingbao in Henan.