370 BC

Year 370 BC was a year of the pre-Julian Roman calendar.

• The Spartans under King Agesilaus II invade Arcadia. After asking the Athenians for help, Arcadia turns to the Thebans. Epaminondas of Thebes comes with an army, finds the Spartan have left and follows them.
• With the support of Thebes, the Arcadian capital city of Megalopolis is completed.
• The tagus of Thessaly, Jason of Pherae, dies.

• The sculptor Praxiteles begins his active career in Athens (approximate date).

• Eudoxus of Cnidus develops the method of exhaustion for mathematically determining the area under a curve.

• Marcus Valerius Corvus, Roman hero
• Theophrastus, Greek philosopher, a native of Eressos in Lesbos, the successor of Aristotle in the Peripatetic school (d. c. 285 BC)

• Agesipolis II, Agiad king of Sparta
• Democritus of Abdera, Greek philosopher (approximate date) (b. c. 460 BC)
• Hippocrates of Cos, Greek physician (b. c. 460 BC)
• Jason of Pherae, ruler of Thessaly