Don't forget that during this time, the Spartans had a system of slavery a lot like that in Pre-Emancipation American South. A child of a slave (Helot) was also a slave. they were recognizably different from their enslavers - in the sense that they looked like Achaean Greeks (big and blond) rather than the peoples who pushed the Achaeans out.

This subjugation of Greeks from the era of the Odessey was an issue for non-Lacedaemonian Greece - and one of the reasons the League banded together.

I dug into this because a good friend, also an amateur historian, but Black (which I am not) was wondering if there was ever a war to free the slaves in the ancient world - and this looks to be it. Something else to remember Epaminondas for.