Hangu Pass sits in a narrow gorge about 75 kilometres west of Sanmenxia, where the Yellow River and the Qinling Mountains create a natural bottleneck that was the strategic key to control between the Zhou states of the east and the Qin state of the west. The pass changed hands repeatedly during the Warring States period; it was here that Qin's westward expansion was most dramatically contained, and here that Qin's eventual eastward conquest began. The rebuilt pass gate (entry ¥80) is a theatrical reconstruction rather than an original, but the gorge scenery that made the location strategically vital is entirely genuine and impressive.
The association with Laozi gives the pass a philosophical layer that attracts Daoist pilgrims alongside the historically minded. A temple marks the supposed spot where the Dao De Jing was written. The journey from Sanmenxia takes about an hour by road; the pass sits just inside Henan's border with Shanxi. The surrounding Yellow River gorge scenery, with its vertical cliffs and the river squeezed between them, is worth seeing regardless of one's feelings about the historical narrative.