[6][7] In a historical work, the expression Piast dynasty was introduced by the Polish historian Adam Naruszewicz; it is not documented in contemporary sources.

The Piasts temporarily also ruled over Pomerania, Bohemia and the Lusatias, as well as part of Ruthenia, and the Hungarian Spiš region in present-day Slovakia.

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.

The senior branch of the Silesian Piasts, descendants of Bolesław III Wrymouth's eldest son Duke Władysław II the Exile, went separate ways and since the 14th century were vassals of the Bohemian Crown.