Between 500-400 BC, the Greek city-states fought several wars including two against the powerful Persian Empire to the east. The Persians invaded Greece twice, first being defeated at the Battle of Marathon in 490 BC and again being stopped temporarily at Thermopylae in 480 BC before being defeated at the naval Battle of Salamis. This marked a turning point where Athens' power grew and it formed an alliance known as the Delian League, but resentment grew against Athenian domination which led to the Peloponnesian War between Athens and Sparta from 431-404 BC, weakening Greece.