Decades: 470s BC 460s BC 450s BC 440s BC 430s BC - **420s BC** - 410s BC 400s BC 390s BC 380s BC 370s BC

Years: 431 BC 430 BC 429 BC 428 BC 427 BC - **426 BC** - 425 BC 424 BC 423 BC 422 BC 421 BC

- Battle of Tanagra - Athenians under Nicias are defeated in an invasion of Boeotia
- Battle of Olpae - Athenians under Demosthenes defeat the Spartans in Aetolia
- Major earthquake in Athens

**Deaths**

- Herodotus of Halicarnassos
- Zhou kao wang, King of the Zhou Dynasty of China