Hmm... I don't know much about your world, but being "low-tech" doesn't mean people wouldn't be able to live on a polar climate. I mean, if you are considering a fantasy world, it could have magic (Does it have?), what would solve most of your problems, cuz magic can be explained just as "Thats magic!!". Of course maybe you don't want magic, or at least not something so "not scientific" basing everything on magic.

In this last case, well, we would have to consider what is "low-tech" for you. I mean, like some folks said on another post when discussing about sawmills and smiths and technology: Tech comes usually from accidental discovering, what usually comes from the needs of finding new things. So maybe you could consider a watermill "low-tech", but for others civilizations it would be a f**ing-awsome-great-thing that would save its life. I'm not saying that maybe your north polar men have invented heater, no, but they could be a tribe of nomads, barbarians, what in this case could live on cold region, but traveling from area to area looking for better climate and more food, yet they wouldn't go farther than a specific area, cuz they know to the south there are enemies of something like that.
Another option is to just move them a little bit to the south. Byt his, I mean a area still cold, but an area that on summer has no snow, so that they can grow plantations, and so food. An are they would have to produce lots of foods on summer so that they would have enough to get trough the cold winter. An area where they don't have cows, but Buffalos, or Llamas - or basic any other cold region animal. In places like that I could see a civilization growing up, maybe not as big as the Roman, but still one with the wish to conquer souther lands, so that they could live all the time with good temperatures.

I don't know if its that what you were looking for, I actually didn't understand what your question was about exactly.