From the Proterii Kniga

[mishalak]

In one of the last acts of the War of the Uprising the city of Pskov was burnt by Bóginki to punish the humans' use of powers forbidden them. They had dabbled previously, but during the war human enchanters took full advantage of the opportunity to call on spirits they normally could not and to work what magics they could. The Bóginki decended from the sky one October day to bring flames and death by their greater powers. Many humans were cut down on the tree-lined roads fleeing to the west. Pskov was reduced to quiet ruins for a century before the humans started to cautiously return to live, though much less boldly than those old residents had.

A few who fled long before the end into the mountains east of Danevar are reputed to survive still. Those lands are deep with strangeness and the Bóginki will not go there, though they do not say why. Those who live there are said to be as fearsome and live by darkness as their opposites live by light. Fearful villagers near the mountains say that these Umpyir come to take away life and spirits from the unwary.