Shanxi Rift System in the context of Normal fault

Guanzhong (Chinese: 关中, formerly romanised as Kwanchung) region, also known as the Guanzhong Basin, Wei River Basin, or uncommonly as the Shaanzhong region, is a historical region of China corresponding to the crescentic graben basin within present-day central Shaanxi, bounded between the Qinling Mountains in the south (known as Guanzhong's "South Mountains"), and the Huanglong Mountain, Meridian Ridge and Long Mountain ranges in the north (collectively known as its "North Mountains"). The central flatland area of the basin, known as the Guanzhong Plain (关中平原; pinyin: Guānzhōng Píngyuán), is made up of alluvial plains along the lower Wei River and its numerous tributaries and thus also called the Wei River Plain. The region is part of the Jin-Shaan Basin Belt, a prominent section of the Shanxi Rift System, and is separated from its geological sibling — the Yuncheng Basin to its northeast — by the Yellow River section southwest of the Lüliang Mountains and north of the river's bend at the tri-provincial junction among Shaanxi, Shanxi and Henan.

The name Guanzhong means "within the passes", referring to the four major mountain pass fortresses historically defending the region. The region was the traditional heartland of Qin state during Zhou dynasty and thus often nicknamed the "800 li of Qin land". The Yellow River, Lüliang Mountains and the eastern end of the Qinling separate the region from the (then) politically orthodox Central Plain, which is located east of the strategic Hangu Pass and therefore was historically referred as the Guandong ("east of the pass") region by the Qin people, who later conquered the eastern states and unified China as a centralized empire — the Qin dynasty — for the first time during the 3rd century BC. Afterwards, subsequent prominent dynasties such as the Han and Tang (both considered China's historical golden ages) also had the crownland established in the Guanzhong region.

The 1556 Shaanxi earthquake (Postal romanization: Shensi), known in Chinese colloquially by its regnal year as the Jiajing Great Earthquake "嘉靖大地震" (Jiājìng Dàdìzhèn) or officially by its epicenter as the Hua County Earthquake "华县地震" (Huàxiàn Dìzhèn), occurred in the early morning of 2 February 1556 in Huaxian, Shaanxi, during the Ming dynasty.

Most of the residents there lived in yaodongs—artificial caves in loess cliffs—which collapsed and buried alive those sleeping inside. Modern estimates by China Earthquake Administration's publications put the direct deaths from the earthquake at roughly 100,000, while over 700,000 either migrated away or died from famine and plagues, which summed up to a total reduction of 830,000 people in Imperial hukou registration. It is one of the deadliest earthquakes and one of the deadliest natural disasters in Chinese history.