The Helots were the peoples who inhabited the lands of  Messenia which neighboured Sparta. Messenia was conquered by the Spartans in 640-620 BC. The Spartans relied heavily on the Helots for survival, so if somebody killed or injured a Helot, it was a serious crime. Politically and legally, Helots had no rights at all. Sparta was free to rid or dispose of them whenever they wanted to. Helots were probably forbidden to go out at night to stop them from plotting secretly against the Spartans. Groups of young Spartans crept about in the dark night with knives, murdering any helots that they found out doors. Sparta needed a fierce army to control the large number of semi slaves, called helots, who produced all the food. The Spartan always forced a slave revolution.