221 BCCenturies: 4th century BC - 3rd century BC - 2nd century BC
- State of Qin conquered the state of Qi. King Zheng of Qin unifed China and proclaimed himself Qin Shi Huang Di (the First Emperor of Qin.) as he was the first Chinese sovereign able to rule the whole country.
- Hannibal succeeds his brother-in-law as commander of Carthaginian Spain.
- Philip V becomes king of Macedonia.
- Gaius Flaminius builds a second racetrack for Rome, the Circus Flaminius.