Casimir I the Restorer
The Polish monarchy had to deal with the expansionist policies of the Holy Roman Empire in the west, resulting in a chequered co-existence, with Piast rulers like Mieszko I, Casimir I the Restorer or Władysław I Herman trying to protect the Polish state by treaties, oath of allegiances and marriage alliances with the Imperial Ottonian and Salian dynasties. The Bohemian Přemyslid dynasty, the Hungarian Arpads and their Anjou successors, the Kievan Rus', later also the State of the Teutonic Order and the Grand Duchy of Lithuania were mighty neighbours.