Russia is a major geopolitical force in the modern world, and has been for centuries.
They are also the largest nation in the world, and famous for many things (The most famous presumably being communism.)
However, I believe that if Russian expansion into Asia had been halted they would be demoted to a regional power, if that.
Could somehow the Hordes unite to conquer Russia?
Or perhaps their colonial ventures prove fruitless and so they don't bother continuing?
Maybe someone else colonizes Siberia first?
Also, considering this would cause Russia not to expand what would happen to Alaska? I would assume British colonization would merely continue and it would be incorporated to Canada, but I'm interested in everyone else's views.
So, how could Russian expansion be prevented?