We have very little archeology and primary literally sources (first accounts from. Sparta) so we rely on the other primary sources some of which are contemporary to. Foreign writers are exclusively male (hardly any female writers) and then they never mention sparta. The ancient greeks said that spartan women were contentious for their freedom (directly addressing men, exercising in the nude) and thus they are often presented as the first liberated women in antiquity. They are often caricatures or exaggerations due to the bias of the writers. Most authors in antiquity are part of the elite and thus have their own interests. Aristotle saw slaves as living tools and the barbarians as being worthy of being ruled and not to rule. Our sources on sparta come from greek historians. The earliest of which is herodotus of miletus. He is writing ethnography or anthropology rather than history.