Qin

State · 750–219 BCE · at its largest around 222 BCE

Western Chinese state in the Wei River valley that grew powerful after Shang Yang's legalist reforms and unified China in 221 BCE.

On its lands while it lasted

Zhou dynasty (1,046–256 BCE): The longest-lasting Chinese dynasty, whose rulers claimed the Mandate of Heaven; real power declined after the move east in 771 BCE.
Spring and Autumn period (770–476 BCE): Era of the Eastern Zhou in which rival states jostled for hegemony, named after the chronicle of the state of Lu.
Confucius (551 BCE – 479 BCE): Philosopher and teacher from the state of Lu whose ideas on ethics, family and government became the foundation of Confucianism.
The Art of War (c. 500 BCE): Military treatise attributed to Sun Tzu, a general associated with the state of Wu; it remains one of the most influential works on strategy.
Nanjing (495 BCE): Capital of Eastern Wu (229–265), Southern Tang (960–976), Ming Dynasty (1375–1644), and 2 more.
Warring States period (475–221 BCE): Era of intense warfare among seven major states, marked by bureaucratic reform, iron technology and flourishing philosophy, ended by Qin unification.
Tao Te Ching (c. 400 BCE): Foundational text of Taoism traditionally attributed to Laozi; most scholars date its compilation to the 4th century BCE.
Mencius (c. 372 BCE – 289 BCE): Confucian philosopher who argued that human nature is inherently good; revered as the "Second Sage" after Confucius.
Chengdu (311 BCE): Capital of Shu Han (224–262), Cheng Han (306–346), Former Shu (911–925), and 1 more.
Qin Shi Huang (259 BCE – 210 BCE): King of Qin who conquered the other Warring States and in 221 BCE became the first emperor of a unified China, standardising script, coinage and measures.
Dujiangyan (c. 256 BCE): Irrigation system on the Min River built by the Qin governor Li Bing; it still waters the Chengdu Plain today.
Emperor Gaozu of Han (Liu Bang) (c. 256 BCE – 195 BCE): Commoner-born rebel leader who founded the Han dynasty and ruled as its first emperor from 202 BCE.
Qin's wars of unification (230–221 BCE): Campaigns in which Qin conquered Han, Zhao, Wei, Chu, Yan and Qi in turn.
Qin unifies China (221 BCE): With the fall of Qi, the state of Qin completed the conquest of the Warring States and founded the first unified Chinese empire.
Qin standard script (221 BCE): After uniting China, the Qin made its small seal script the standard writing of the whole empire, a step toward one written Chinese used across many spoken languages.