Wei River Plain

Japanese: 渭河平原 - いがへいげん

…It is a depression basin between the Loess Plateau and the Qinling Mountains, stretching 300km east to west and 100km north to south. It is also called Guanzhong or the Weihe Plain. The term Guanzhong was used at the end of the Warring States period to refer to the area bounded by Hangu Pass in the east, Sanguan Pass in the west, Xiao Pass in the north, and Wuguan Pass in the south. …

From [Guanzhong]

…the Wei River Plain in Shaanxi Province, China. It is said that the name was derived from the area between Hangu Pass in the east and Long Pass in the west, which is also connected to Hangu Pass in the east, Wuguan Pass in the south, Sanguan Pass in the west, and Xiaoguan Pass in the north, and is synonymous with the area within the region. …

*Some of the terminology used to refer to the Wei River Plain is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…黄土高原，秦嶺にさえぎられた陥没盆地で，東西300km，南北平均100km。関中，渭河平原ともいう。関中の語は戦国末には使われ，東の函谷関，西の散関，北の蕭関，南の武関に囲まれた地域をさす。…