Grailknight is correct. Transylvania is in the Mountainous regions of Romania, and not Russia. This, however, is Warhammer....

I picked them purely because of the Eastern European accents of the troops, and because they had to be some faction

There is ABSOLUTELY NO RELATION between the factions and their chosen sides. Except where I felt that th egame had some existing feature that would fit. Like choosing Egypt for the Tomb Kings...