Delving into the history of the Spartans is not easy. They left practically no written sources, and everything we know comes from what the ancient Greeks wrote and built over time. In the popular imagination, there is the terrible battle against the Persians, Thermopylae. In the pass of Thermopylae, King Leonidas and three hundred Spartans led seven thousand Greeks to hold back an immense Persian army until reinforcements arrived. Among the Persians were combatants from 46 nations, and the Spartans, according to Aristophanes, fought like furious beasts, with foam running down their jaws and legs.