Thunderfrost Mountains

In the far north of Fellheim, nearly as far north as one can go, are the Thunderstone Mountains. They are named with simplicity in mind, in consideration of the two traits of the area. Given the latitude, the climate is understandably frigid. As to be expected with such conditions, snow and blizzards are commonplace. More to the point, the snow is near unceasing (albeit sometimes light), the runoff of which feeds several rivers.
Unfortunately for travelers, the snow is unceasing, and the blizzards are rather frequent across the tundra that leads up to the mountains, as if a sandstorm of frost and snow whipped across the barren ground.
The unrelenting winds and near-blinding snow make travel treacherous, and that's before you even reach the base of the mountain range. Once there, one has to deal with the addition of a climb, thinning air, and the threat of avalanches due to the snowfall. As if this were not enough to make anyone reconsider, after a certain altitude, thundersnow becomes commonplace. It was as if the gods themselves thought that they would test the very limits of mortality by creating a trial so arduous that even saints and guardians wouldn't attempt it without much preparation and an extremely good reason.
Blizzard conditions, thinning air, and the ever-constant threat of lightning strikes will keep most at bay, and kill nearly all foolhardy enough to attempt to ascend the slopes, but that is a story of its own.
Yet, all is not lost. Dwarven ingenuity by name of Veins of the Mountain have been established along the most common routes, and what those don't cover, mages traveling with their convoys will. The engineers did not bother creating rails to ascend to the top, for several reasons.

Geography

A rocky and frozen mountain range, it is difficult to tell what is rock from what is ice without the use of some sort of magic or tool.

Ecosystem Cycles

This region has 2 distinct seasons: What most consider to be summer, in which the snow is not as heavy, the sun occasionally peeks through the clouds, and travel via multiple methods is possible. The other season is what the rest of the world would think of as winter. In this particular region, it is call Nil, for the amount of travel that can be done outside of Dwarven rails or airships, and even traveling via airship is unwise, courtesy of the frequirent thundersnow.

Localized Phenomena

This is the only place in the world in which thundersnow, snow with lightning, occurs.

Climate

"Cold" is generally an understatement. During the dead of winter, one does not venture outside of a city without doing so on a train, and even then, seeing one's breath while inside is considered "a warm ride". Trying to travel outside without some sort of divine protection will invariably result in severe hypothermia, and likely death after mere hours.
It's climate is so brutally cold and inhospitible that those who grew up within the region scarcely believe and cannot fathom the notion of 'tropical' weather.

Natural Resources

The area is extremely mineral rich, though surface deposits are an obvious danger to mine. Most of the resources in this region are gathered from within the mountains.

Tourism

Only those who wish to die as an extremely lifelike sculpture would visit this place as a mere tourist.

Type

Mountain Range