Yang Pass

Yangguan, or Yangguan Pass (traditional, simplified, lit. 'Sun Gate'), is a mountain pass that was fortified by Emperor Wu of the Western Han dynasty around 120 BC and used as an outpost in the colonial dominions adjacent to ancient China. It is located approximately 70 kilometres (43 mi) southwest of Dunhuang, in the Gansu territory to the west of the Shaanxi province in the far Northwest China, which was in ancient times the westernmost administrative center of China. It was established as a frontier defense post, as well as a developed place in China's remote western frontier; Emperor Wu encouraged Chinese to settle there. Today Yangguan is located in Nanhu Village, along the Hexi Corridor. Yangguan was one of China's two most important western passes, the other being Yumenguan. In Chinese, yang means "sun" or "sunny", but it can also be used to mean "south" (the sunny side of a hill being the southern side). Yangguan was therefore so-named because it lies to the south of the Yumenguan Pass. It was an important landmark on the Silk Road. The fortress at Yangguan however had fallen into ruin by around AD 900.

Building data from Wikidata (CC0); heights normalised. Summary from Wikipedia (CC BY-SA).