The Crisis of the Third Century in Rome, the Sasanian Empire's rise, and China's Three Kingdoms era.
Notable 3rd Century Milestones
- 245 Apr 03: -BC- Origin of Era of Arsaces.
- 241 Mar 10: -BC- Battle of Aegusa Roman fleet sinks 50 Carthagean ships.
- 240 Jun 19: -BC- Eratosthenes estimates circumference of Earth.
- 284 Aug 29: Origin of Era of Diocletian (Martyrs).
- 239 Mar 30: -BC- inaugural recorded perihelion passage of Halley's Comet.