The Wiksekka Mountains form the southern boundary of the Kurushat region. Since Kurushat is located on the southwestern corner of my map, it's effectively the boundary of my entire setting, at least in that corner. This begs the question... what's past it, and why isn't it detailed?
According to many esoteric theories throughout the region, humanity isn't the first race to haunt these lands. Even the Neanderthals who wander the Kvuustu steppes are newcomers compared to Those Who Came Before. The nature of Those Who Came Before is mysterious, but faint clues of their existance percolate up from the depths of Deep Time occasionally, to mystify and frighten humanity. Many believe that the Plateau of Leng in the Forbidden Lands is a legacy of Those Who Came Before. Most likely, so is the land south of the Wiksekka Mountains.
The lands to the South are blighted beyond all recognition, and it is possible that they are so inimical to regular life as we know it, that literally nothing can survive here. Strange atmospheric effects and other bizarre astronomical oddities range the gamut from extraordinary to strange to outright impossible--and yet they occur regardless. The air is very thin here, and possibly poisonous to those who manage to survive it for any length of time. Bone-searing cold grips the land in an ice that is made up of water, as well as carbon dioxide and other compounds that don't normally freeze on the surface of the earth at all. Strange eruptions of gas and crystaline faults hint at some kind of geological activity of the surface, but these gaseous vents bend sharply in wind shears high above the surface.
This line of thought leads rather ominously to the possiblity of alien entities entering our world through this patch of strange, cold land. Some scholars in the past, before their research was suppressed and burned, believe that semi-legendary figures like the wendigo or the gnoph-keh are exactly that--creatures of extrawordly extraction that slipped through the Wiksekka Mountains to plague the world beyond.