The Spartans were Doric Greeks, who came from the north, and conquered and colonized a place in the Peloponessis named "Lakonia." Reportedly, they conducted wars against the "Helots," who had the same name as that of their own serfs or servants. The Helots were apparently the descendants of earlier Achaean Greeks, such as the ones that fought the Trojan War, before their societies were weakened by something. That may have been long droughts, earthquakes, or volcanoes.
After the Romans conquered Greece, the Spartans, like other Greeks, became their subjects. There's a story about a slave who wa named "Spartacus," who led a slave revolt in Italy.