The background is maintained here.
The Varangur are a tribe of humans living near the Ice Mountains of northern Mantica. Long before the God War, most humans living in this area moved south and became part of Primovantor. The Varangur, however, refused to do so, remaining in their old lands. This awakened the interest of an ancient god.
When the Celestians first arrived on Mantica they set about defeating the terrible things that wreaked havoc across the land. One of these things was an ancient god named Korgaan. Korgaan was worshiped by an ancient race known as the Var'Kyr. The Celestians wiped this race out and sealed Korgaan away, leaving him to slowly perish as his power diminished from lack of worshipers. Although Korgaan was fading from existence by the time he began influencing the Varangur, he was able to stem this tide and began to recover his former power. When the Fenulian Mirror was shattered, Korgaan was able to move more rapidly without worry since every other god was busy trying to win the God War. Korgaan began to appear to the Varangur in the shape of three divine beings: the Deceiver, the Reaper, and the Warrior.
Korgaan began to reshape their culture in the image of the Var'Kyr. The rest of the world did not notice this as they were embroiled in their own conflicts and Korgaan only seemed interested in having the Varangur run small scale raids into the south. All of this changed when the Winter War broke out.
While the Northern Kindred and Brotherhood were busy fighting Winter's minions, the Varangur began launching full scale assaults into their territory and towards the Golden Horn. Realizing that this was a force unaligned with Winter, the High Consul of Primovantor sent a great fleet north to destroy this nuisance once and for all. Unfortunately for them, this fleet was en route when Winter was killed, leading to it being swallowed by the newly formed Infant Sea and, in many ways, ensuring that Primovantor would fall in the chaos that followed.
The Varangur were caught in the seismic upheaval themselves, forcing Korgaan to expend most of his power just to prevent their main settlements from being destroyed. His people now fearful and uncertain for the first time in centuries, Korgaan appeared to the clans and ordered them into Tragar. Pushing past the Abyssal Dwarfs, the Varangur invaded the first circle of the Abyss, shocking both the Shining Ones and the Wicked Ones alike.
In what would become known as "The Reckoning," the Varangur ravaged the outer circle of the Abyss, slaughtering the followers of the Wicked Ones and seizing whatever they could take. It was a defeat worthy of Abaddon and invigorated the Varangur. Content that his power and influence over the Varangur was no longer in danger, Korgaan declared victory over the Abyss and promptly left back to the north.
In the current time of Kings of War the Varangur have gone back to running smaller raids into the lands south of them. Their current major foe is the Northern Alliance, but their forces are often seen even in places like the Forest of Galahir and the Golloch Empire.