In retrospect it almost seems like ASBs intervened to permit Muscovy to gradually swallow up its rivals in the European plains, and then transform itself into the Tsardom of Russia which remarkably quickly expanded across the entire Eurasian landmass.
So how could this process be prevented, with the result that the map of OTL European Russia resembles the map of Central Europe? Bonus: the POD must occur *after* the fall of the Mongol Empire, since the Mongols wiped out so many polities which could have prevented the political unification of the region.
EDIT: made mistake about Mongol Empire.