The period of the 5th century BC in classical Greece is generally considered as beginning in 500 BC and ending in 404 BC, though this is debated. This century is essentially studied from the Athenian viewpoint, since Athens has left more narratives, plays and other written works than the other Greek states. If one looks at Athens, our principal source, one might consider that this century begins in 510 BC, with the fall of the Athenian tyrant and Cleisthenes's reforms. If one looks at the whole Greek world, however, we might place its beginning at the Ionian Revolt in 500 BC, that provoked the first Persian invasion of 492 BC. The Persians (called "Medes") were finally defeated in 490 BC. A second Persian attempt failed in 480–479 BC. The Delian League then formed, under Athenian hegemony and as Athens' instrument. Athens' excesses caused several revolts among the allied cities, which were all put down by force, but Athenian dynamism finally awoke Sparta and brought about the Peloponnesian War in 431 BC. After both sides were exhausted, a brief peace occurred, and then the war resumed to Sparta's advantage. Athens was definitively defeated in 404 BC, and some internal Athenian agitations ended the 5th century in Greece.