Hangu Pass

Hangu Pass or Hanguguan was a fortified gateway that commanded the strategic mountain pass between the Yellow River and Qinling Mountains, forming the main choke point on the only land corridor between the Central Plain and the Guanzhong region. The pass restricted access into the lower Wei River valleys, where the heartland of the state of Qin and the unified Qin dynasty were located, as well as the subsequent dynasties of Han, Sui and Tang. The Hangu Pass lies on the south (right) bank of the Yellow River, 60 km (37 mi) downstream of its eastward bend out of the Ordos Loop. It was built by the state of Qin in 330 BC and had been the site of many sieges and field battles during the Warring States period and early imperial eras. Due to terrain changes from bank erosions and alluvial deposition of the Yellow River over the centuries, the Hangu Pass eventually fell to ruins after losing its defensive values to the newer Tong Pass to its west, which was built near the mouth of the Wei River in 196 AD by the warlord Cao Cao. The term "Hangu Pass" can mean to two locations: the Qin-era Hangu Pass in Hanguguan Town, Lingbao County, Sanmenxia, Henan province; and secondly, the Han-era Hangu Pass in Xin'an County, Luoyang, Henan. Traditionally, the term refers to the former. In 2014, the archeological site was recognized by UNESCO as part of the “Silk Roads: the Routes Network of Chang'an-Tianshan Corridor” World Heritage Site.