421
| Years: 417 418 419 420 – 421 – 422 423 424 425 | |
| Decades: 390s 400s 410s – 420s – 430s 440s 450s | |
| Centuries: 4th century – 5th century – 6th century | |
Events
- February 8 – Constantius III becomes Co-Emperor of the Western Roman Empire
- June 7 – Roman Emperor Theodosius II marries Aelia Eudocia, formerly known as Athenais.
- Theodosius declares war on Persia.
- Traditional date of the foundation of Venice. (The real foundation may well have been over a century later.)
Births
Deaths
- September 2 – Constantius III, Co-Emperor of the Western Roman Empire
- Emperor Gong of Jin China
Categories: 421