The Greek civilization originated in the Balkan Peninsula and islands of the Mediterranean in the 8th century BC. They lived in independent city-states called poleis, with their own governments like Athens and Sparta. Poleis were initially ruled by aristocracies but some later transitioned to democracies. During a period of overpopulation and famine, many Greeks migrated and established colonies across the Mediterranean, spreading Greek culture and influence. Greek society was divided between citizens and non-citizens including foreigners, slaves, and women who had few rights.