In OTL, Siberia, except for a few regions, is a barren wasteland with a small village every 50-100 kilometers. What would lead to Siberia and the northeastern part of Europe being populated as dense as Europe?

Note: It is my Medwedian timeline. Humans are replaced by humanoid bears. Medwedia is a country which takes up the northern part of Russia, spanning from Nordkap to Alaska. I wish that both the Medwedian (northern) and Russian (southern) parts of Siberia are densely populated.