Cultural what?

I agree that the expression "cultural relativism in antiquity and the early modern period" is a rather cumbersome one. I promise that I'll try to use it only in emergencies.
However, what I intend is rather simple.
Consider, for instance, Montaigne's essay on cannibals, and his relativist look at different societies in the second part of the 16th century. As a start, I can imagine some questions: from where did these sorts of ideas come from? Who are Montaigne's antecedents? How "savage" cultures were considered in antiquity? Which cultural frameworks were used to make sense of outsiders? What was the impact of voyages, and exploration?