Sixteen Ways to Defend a Walled City

Is there a term similar to “secondary world fantasy” for stories with no fantastic elements, but set in a non-Earth world? Secondary world historical fiction maybe? Anyway, this is that. Quick, clever, and enjoyable. Gets a bit of side eye for making the aristocratic ruling class (Romans or Byzantines, basically) black and the subjugated lower classes white. Different world, different history, different arbitrary hierarchy, yeah, but uncomfortable, and I don't think a good way.