431 BC

Centuries:	6th century BC · 5th century BC · 4th century BC
Decades:	460s BC 450s BC 440s BC 430s BC 420s BC 410s BC 400s BC
Years:	434 BC 433 BC 432 BC 431 BC 430 BC 429 BC 428 BC

Events

Athens enters into an alliance with King Sitalkes of Thrace, after Nymphodorus, an influential Athenian, marries Sitalkes’ sister. Nymphodorus then negotiates an agreement between Athens and Macedon’s King Perdiccas, through which Perdiccas regains Therma. As a result, Athens withdraws its support for Perdiccass’ brother, Philip, and the Thracians promise to assist Perdiccas in capturing him. In return, Perdiccas marches on the Chalcidians, the people he had originally persuaded to revolt.
A Theban raid on Plataea, the only pro-Athenian city in Boeotia, is a failure and the Plataeans take 180 prisoners and put them to death. Athens supports Plataea while Sparta aligns itself with Thebes. Sparta enlists the help of the Greek cities in Italy and Sicily. Both Sparta and Athens appeal to Persia, but without result.
The Spartans led by King Archidamus II invade Attica effectively starting the Peloponnesian War between the Athenian Empire and the Peloponnesian League. The Spartans lay waste to the countryside around Athens. Athenian leader, Pericles, does not seriously oppose them, rather withdrawing the rural population of the country districts within Athens’ city walls. Instead, he pursues active naval warfare and reduces any danger from the island of Aegina by replacing its native population with Athenians.

The Romans defeat the Aequi and the Volsci at the battle of the River Algidus. ^[1]

The Greek physician and philosopher Empedocles articulates the notion that the human body has four humours: blood, bile, black bile, and phlegm, a belief which dominates medical thinking for centuries.

Euripides' play Medea wins third prize at the Dionysia, the famous Athenian dramatic festival.

^ Mellersh, H.E.L. (1976). Chronology of the Ancient World. Barrie & Jenkins, pg 128. ISBN 0214200884.