Pathfinder: Reign of Winter
Irrisen is Pathfinder Russia. A thousand years ago, lands were stolen from the Ulfen by the witch Baba Yaga over a period of mere months. Baba Yaga then placed a daughter of hers on the throne of Irrisen and departed to travel between words or do whatever it is immortal witches do.
Irrisen is in the perpetual grip of winter and is ruled by the White Withes, who are all children or grandchildren or distant relations of Baba Yaga’s. Called the jadwiga, females have a natural affinity for spellcasting. A few males become White Warlocks, but most become military commanders and warriors of renown.
The jadwiga use cold fey and trolls as enforcers, spies and servants. Every hundred years, the Three Riders, White, Red and Black, travel through Irrisen testing the people’s loyalty and killing those who fail the test. Then Baba Yaga returns and places a new daughter on the throne.
For Irrisen, think of the Soviet Union behind the Iron Curtain + Narnia under the White Witch.