Qin

In 221 BCE, King Zheng of Qin conquered the last rival states and called himself the First Emperor, founding China's first centralized empire.

One script for writing, one gauge for axles, one set of weights and coins; highways radiating from the capital, walls joined into the Great Wall, and commanderies replacing feudal lords — the First Emperor carved the word "unified" into the next two thousand years of China.

But harsh laws and endless labour soon lit a rebellion. Chen Sheng and Wu Guang rose at Dazexiang; Xiang Yu and Liu Bang followed. The mighty Qin lasted only fifteen years.