Bostrova

Bostrova is a freezing cold island far in the northeast of Kashura, belonging to the Kazovka region of The Devoj Wilderness. Temperatures on Bostrova pretty much never go above freezing and can dip as low as -50C (-58F) during the harshest winter months. Blizzards are a common sight even during calmer seasons, making it an all-around miserable place to live, yet it is still home to Vitra, a prison colony of The Astarojna Dominion.
The reason for this is simple, the mountains of Bostrova are quite rich in silver tin, and are the dominions primary source of both materials.