Trying too hard to avoid cliche?

[Triplicate]

I was thinking about how to make a fantasy world that didn't rely on strict counterpart cultures. Problem is, I tend to think in terms of counterparts, possibly since I spend more time thinking about geofiction.

I realized that my goals could often be achieved by separating aspects of a culture or nation. For example, if I want the world to have a Rome counterpart, what I really mean is that I want a large, expansionist republic with above-average infrastructure. I don't mean I want to duplicate their religion, architecture style, etc. A nation can be very different internally and fill a similar role in the world.

But what of trying harder? Inspired by my sword-and-planet dream world, I was still thinking about ways to avoid the "barbarians from the frigid Northlands". I thought, "I want an Arctic nation that can stand up to its counterparts from the south".

Then I realized how implausible this was. And it showed something about why I don't find making low-tech fictional worlds fun: there's not much freedom, because people have to work within the boundaries imposed by nature. In this case, as usual, it's agriculture. If you live so far north agriculture is marginal to impossible, you can't support a large population density. You're even worse off than usual in terms of supporting workers who don't supply food. Barring unusual biology, advanced technology or magic not available to others, the polar civilizations can't be a match. And then I remember why. In terms of alien planets, I know that "extremes" are subjective. They're seen from the perspective of what climate a species is adapted for. But humanity began in East Africa, near the equator. As long as I'm restricted to working with humans, polar climates remain extreme.