Ancalagon
Dusty Dragon
I, for one, would be bothered by this. I remember, many many years ago, we did a 2nd ed Ravenloft module in a domain where it was "always winter" - for the last 30 years. I immediately challenged it (I was a bit of a hothead back then) pointing out that if it had been winter for 30 years, everyone would have died of starvation. The GM was not amused.
As far as to making this vaguely plausible, I recommend reading up on the very high altitude communities in Tibet. Barley will grow up to 5000 metres. Yaks can be moved from valley to valley to graze. Yak butter (a sort of cheese-butter hybrid), tea and barley are the staple foods. If it's livable, people will live there, history has shown us this. However, if it's far north and high in altitude, it becomes a bit... less plausible.
So your next question is this: Is the Yakfolk village exceptional, or just the one that happens to be there near the PCs' path? Meaning are there 100s more of little such northern villages, just that the PCs won't visit them because they aren too far? Then consult the above. If the yakfolk village is unique, then there has to be a reason for it to be there beyond "there is marginally usable land here". Then you can start considering magical (maybe divine?), or special environmental factors (someone mentioned hot springs).
As far as to making this vaguely plausible, I recommend reading up on the very high altitude communities in Tibet. Barley will grow up to 5000 metres. Yaks can be moved from valley to valley to graze. Yak butter (a sort of cheese-butter hybrid), tea and barley are the staple foods. If it's livable, people will live there, history has shown us this. However, if it's far north and high in altitude, it becomes a bit... less plausible.
So your next question is this: Is the Yakfolk village exceptional, or just the one that happens to be there near the PCs' path? Meaning are there 100s more of little such northern villages, just that the PCs won't visit them because they aren too far? Then consult the above. If the yakfolk village is unique, then there has to be a reason for it to be there beyond "there is marginally usable land here". Then you can start considering magical (maybe divine?), or special environmental factors (someone mentioned hot springs).