So we see an evolved Spartan Republic, perhaps by 650 B.C, consisting of a balanced political system built to support a militaristic ideal.
So much of it was eccentric: the anachronistic twin royal houses that lived on past their time, the Ephors, commoners elected by the shouts of the populace, and the odd relationship between Sparta, the Perioikoi, and the Messenians. But still the power of Sparta survived for centuries until the its army became weak in battle. The end came in 371 B.C. when a Spartan army of only 800 Homoioi was utterly defeated at Leuctra.
Victory on the Peloponnesian War had been an illusion. The Spartans could not rule others because their eccentric system did not prepare them for the task. Thirty years later, Spartan power had ended.