Guanzhong

Guanzhong Plain traditionally includes the central part of modern Shaanxi province and the extreme northwestern tip of Henan province (the western half of Sanmenxia). The average altitude of the region ranges from 300 to 700 m (980 to 2,300 ft) above sea level. Xi'an, the provincial capital of Shaanxi and the largest city in Northwest China, is located at the center of the region, mostly south of the Wei River. Other major prefectural cities in the Guanzhong region include (from west to east) Baoji, Xianyang, Tongchuan and Weinan.

The four major historic fortifications that enclose Guanzhong region are:

• Hangu Pass (函谷關) to the east, in present day Lingbao City;
• Wu Pass (武關) to the southeast, in present day Danfeng County;
• Xiao Pass (蕭關) to the northwest, in present day Jingyuan County, and;
• Dasan Pass (大散關) to the west, in present day Chencang District.

Two more passes were later added, namely:

• Tong Pass (潼關) further to the east, built during the late Eastern Han dynasty by the warlord Cao Cao, in present day Tongguan County, and;
• Jinsuo Pass (金鎖關) to the north, built during the Tang dynasty, in present day Yintai District.

Historically the most important fortress of the above passes was the Hangu Pass, which commanded the chokepoint on a narrow land corridor along the south bank of Yellow River and what was then the only traversable passage into the Guanzhong region from the North China Plain. The formidable resilience of the Hangu Pass was what enabled the Qin state to defeat numerous anti-Qin alliances formed by its eastern enemy states during the Warring States period.

China during the warring states period. Guanzhong (Qin) is the southeast corner of the rectangle formed by the Yellow and Wei rivers.

The Guanzhong region became the heartland of the Zhou after Jī clan leader Gugong Danfu relocated his people south from Bin (modern day Binzhou, Shaanxi) to evade the violent raidings by Xunyu, Xianyun and Di nomads. It is from Guanzhong region that the Zhou state prospered and eventually conquered the Shang dynasty to establish the Zhou dynasty in 1046 BC.

After the Quanrong nomads, with collaboration from Marquess of Shen, killed King You of Zhou and sacked the Zhou capital Haojing in 771 BC, the Western Zhou dynasty collapsed and the surviving Zhou court fled east to Luoyi. The Yíng clan, then a minor marcher vassal based in the Longxi Basin as a buffer state on the western frontier of the Chinese civilization, sent troops to escort King Ping of Zhou along the journey. In gratitude, King Ping granted a mid-level nobility to the Yíng leader, Count Xiang, and promised him authority to permanently claim any lands his clan can recapture from the nomads. The resultant Qin state then spent the next few centuries fighting off various nomads to its north and west and eventually consolidated its base in the Guanzhong Plain and the Loess Plateau. The Qin capital then relocated progressively east from Qinyi (in modern Qingshui County, Gansu) to Yong (in modern Fengxiang County, Shaanxi), then to Yueyang (in modern Yanliang District of Xi'an, Shaanxi), and eventually to Xianyang northeast across the Wei River from the ruined old Zhou capital of Fenghao. Four passes were then built to defend this new heartland against hostile attacks from both the east and the west.

During the Warring States period, Qin grew powerful under Shang Yang's legalist reforms, and militarily became increasingly more successful, and its rivals to the east claimed that the Qin army was a "troop of tigers and wolves", and it was often said that "Guanzhong produces generals; Guandong produces ministers". After constructing irrigation systems such as Zhengguo Canal, the already fertile Guanzhong region became extremely productive, allowing Qin state to become the preeminent power, repeatedly defeating and seizing more territory from its rivals to the east, and eventually unified China and established the Qin dynasty in 221 BC.

After First Emperor's death, the Qin dynasty soon fell into chaos due to the corrupt rule of Qin Er Shi and Zhao Gao, and various rebellions broke out. In 206 BC, the rebel leader Liu Bang successfully invaded Guanzhong and forced the last Qin ruler, Ziying, to surrender the capital Xianyang, ending the Qin dynasty. Liu Bang entered the capital peacefully, and issued strict orders forbidding his troops from looting and harming the locals. However, he was forced to hand over the control over to another more powerful rebel leader Xiang Yu, who sacked, pillaged and torched Xianyang before enfeoffing the Guanzhong region to three surrendered Qin generals Zhang Han, Sima Xin and Dong Yi, collectively known as the "Three Qins". However, merely four month later, Liu Bang returned with his newly appointed generalissimo Han Xin and reconquered the Guanzhong region, and used it as his base to eventually defeat Xiang Yu in the subsequent civil war. After establishing the Han dynasty, Liu Bang created a new capital named Chang'an, which is just across the Wei River from the ruined Qin capital Xianyang.

Since the Western Zhou dynasty, the area was the capital region of China for a total of 12 dynasties including the Qin, Western Han, Sui, and Tang. By the Tang dynasty the economic center of China had shifted south to the Yangtze basin and Guanzhong became increasingly dependent on supplies transported 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.[2]

• Three Qins
• Guanzhong Hua
• Wei River