Guanzhong (simplified Chinese: 关中; traditional Chinese: 關中; pinyin: guānzhōng, literally 'pass, center'), or Guanzhong Plain, is a historical region of China corresponding to the lower valley of the Wei River. It is called Guanzhong or 'within the passes' to distinguish it from 'Guandong' or 'east of the pass', that is, the North China Plain. The North China Plain is bordered on the west by mountains. The Yellow River cuts through the mountains at the Hangu Pass separating Guanzhong from Guandong. During the Warring States Period Guanzhong was the western edge of Chinese civilization and was controlled by the state of Qin. As Qin became more militaristic its enemies claimed that it had adopted barbarian customs and was not fully Chinese. It was said that 'Guanzhong produces generals and Guandong produces ministers'. The state of Qin united China and Guanzhong was the center of the Qin and several later dynasties.
The Passes that enclose Guanzhong are:
- Xiao Pass (萧关/蕭關) to the north,
- Hangu Pass (函谷关/函谷關) to the east (see also Tongguan County),
- Wu Pass (武关/武關) to the south, and
- Dasan Pass (大散关/大散關) to the west,
Historically the most important pass was the eastern one along the Yellow River which separates Guanzhong from the North China Plain. Guanzhong includes the central part of Shaanxi and the extreme west of modern Henan.
The average altitude of the Guanzhong Plain is around 500 metres. Xi'an, the capital of Shaanxi, is the largest city in the Guanzhong plain, which also contains the cities of Tongchuan, Baoji, Xianyang and Weinan.
The plain was the central region of the Qin during the Warring States period. Having fertile soil and good irrigation systems, Qin rose from this region to gain preeminence among the Warring States, and eventually unified China. Since the Zhou Dynasty, the area was the capital region of China for a total of 12 dynasties including the Former Han Dynasty, Sui Dynasty, and Tang Dynasty. By the Tang Dynasty the economic center of China had shifted south to the Yangtze River basin and Guanzhong became increasingly dependent on imports via the Grand Canal. After the destruction of Chang'an in the last years of the Tang, Guanzhong became less significant politically as well as economically in later dynasties.