Classical Athens, known contemporaneously simply as Athens, was the major urban centre of the notable polis (city-state) of the same name during the classical period of ancient Greece, located in Attica, Greece, leading the Delian League in the Peloponnesian War against Sparta and the Peloponnesian League. Athenian democracy was established in 508 BC under Cleisthenes following the tyranny of Isagoras. This system remained remarkably stable, and with a few brief interruptions, it remained in place for 180 years, until 322 BC. The peak of Athenian hegemony was achieved during the Age of Pericles in the 440s and 430s BC.