Greek civilization emerged in Southeastern Europe and gave rise to classical civilization. The Minoan civilization on Crete influenced the Greeks and traded extensively. After a volcanic eruption, the Mycenaeans invaded Crete and established separate city-states. Two influential city-states were Sparta, a militaristic society ruled by two kings and elders, and Athens, which developed democracy under Solon and Cleisthenes. The Persian Wars united the Greeks against Persia and allowed Athens to emerge as the most powerful city under Pericles, though this dominance led to war with Sparta. Alexander the Great then conquered Persia and spread Greek culture across his vast empire, establishing the long-lasting Hellenistic civilization.