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
