Sparta conquered Messenia around 640 BC 620 BC. The conquered Messenians became agricultural and domestic slaves and sometimes served as military servants as well. The Messenians became state-owned slaves who lived in their master's household. Unlike regular slaves, their master could not declare them free. The Helots were required to produce a quota of agricultural products and became the backbone of Sparta's agricultural economy. The Spartans usually allowed agricultural helots to keep the excess produce.
The Helots outnumbered the Spartans by as much as 20 to 1. The Spartans kept themselves in continuous military preparedness in order to crush any attempt of rebellion. They hesitated to join military campaigns far from Sparta for the same reason. A military force known as Krypteria kept the Helots under control. According to Aristotle, Spartans redeclared war against them every year to justify the use of force.
In wartime Helots served as light infantry and as rowers in ships. During the Peloponnesian War they fought as heavy infantry and Helots who excelled in battle could earn their freedom. Some 2000 were freed and reputedly later assassinated.
Helots were Peloponnesian Greeks enslaved under the Spartan rule. The first Helots were Laconians whom Sparta defeated and conquered. It is possible that the name Helot comes from Helos, the main city in Laconia.