The Coldfells is a region of the Kostaigne Desert, generally considered to be the southern part of it that is south of the Usymna River and north of Celobsil. It is a generally flat, though undulating land of small lakes, barren rocky outcrops and small coniferous forests. Summers are short and rainy, and winters are long and hard. Crops cannot be grown in the post-glacial soil (and the season is too short) so most of the inhabitants subsist on hunting and foraging, and cultivating quicker growing and hardier plants.
The inhabitants are short of stature and generally wiry, and dwell in yurts beside lakes, rivers and other permanent water sources. Like their kin in the Sjeivakh Lakelands and the Kostaigne Tundra, they are known simply as the Kostaigne. They speak a language that is mostly mutually intelligible with Ghanandese prompting some to believe there is a cultural and racial link.
Economically, it is the region of Invinni where most precious metals such as platinum and palladium are found, the mines of Makael being depleted. Due to its remoteness and the difficulty in getting there, Aesedra has never really ventured here politically.
Of a more grievous nature, it is the ultimate location where woman (and the rare male) kidnapped for slavery are taken. The Kostaigne of the Coldfells are always almost men. To procreate, they buy enslaved women from the Heddig slave markets. Girls are usually slain at birth, whereas the boys are kept as raised as sons and successors. As such, the cultural mix of most Kostaigne south of the Usymna River is a melange of all peoples, though they do tend toward shortness.
Women taken as slaves are fed a mind-destroying drug called sial which is brewed by a rogue cabal of alchemists in Heddig. Sial renders its victims placid and compliant though it needs to be taken regularly to remain effective. Due to the wealth generated by platinum sales, the Kostaigne of the Coldfells can readily afford the price the alchemists charge.
Few in the Empire realise that the platinum and palladium of their jewellery was bought and paid for by the pain of lifelong slavery.
The Coldfells is not a land for casual travel, and any interlopers there without the Kostaigne's blessings are inevitably slain or enslaved at the hands of these skilled and ruthless warriors.