Edad Oscura
The polis or city-state of Sparta was formed during the Greek Dark Ages, controlling the plains around the Eurotas river. Those communities already existing in the area which could not be assimilated into the Spartan state, or subjugated as helots, became the perioeci. Whether they were Dorians like the Spartans, or descended from pre-Dorian populations in the Peloponnese, is unknown.