I'm from the cold north Finland to be specific. I've wondered why did people back in the day decide to stay in cold climates? I mean why not just walk to more warmer ares? Before we had countries etc.

Is there any research to what is though to be the main cause for people like the inuits, sami, early Swedes, Finns etc. staying in these cold climates?

I understand that back then the concept of being Swedish, Inuit etc. didn't exist but to simplify what I mean I decided to use these terms.