As a historian, as a former SCAdian (medieval re-enactor), as someone who likes neomedieval fiction, the question I’ve seen pop up the most is: What did people in the past do about issues like menstruation? Most SCAdians use modern products under their historical clothing, and fictional series can ignore it. But obviously real people didn’t have that luxury.
This isn’t a comprehensive study of every time and culture (though if someone wants to pay me to do that. . . ). Instead, this is the kind of info you can use to inform your ideas about Game of Thrones or Skyrim characters. Menstruation through largely a historical European lens.