Have the Hohenzollerns pull a Habsburg and inherit Poland Lithuania in the fifteenth century. From there it's simply a matter of subjugating Pomerania and Silesia and maybe conquering or inheriting Bohemia or Hungary.
Said state would probably be more of a Russia though- big, vast eatern expanses, relatively populated western area.
Alternately go back and screw ottonian Germany so the Polabian Slavs stay independent, then have a strong Poland gradually annex them, putting the Polish-German border on the Elbe. They probably also control Bohemia in this scenario.
Said state would probably be more of a Russia though- big, vast eatern expanses, relatively populated western area.
Alternately go back and screw ottonian Germany so the Polabian Slavs stay independent, then have a strong Poland gradually annex them, putting the Polish-German border on the Elbe. They probably also control Bohemia in this scenario.