During the subsequent Potsdam Conference in July–August 1945, the three major Allies ratified the colossal westerly shift of the Polish frontier and approved its new territory between the Oder–Neisse line and Curzon Line, which resulted in the Polish borders shrinking and resembling those of the former Piast dynasty era. Following the destruction of the Polish-Jewish population in the Holocaust, the flight and expulsion of Germans in the west, resettlement of Ukrainians in the east, and the expulsion and resettlement of Poles from the Eastern Borderlands ("Kresy"), Poland became for the first time in its history an ethnically homogeneous nation-state without prominent minorities. The new government solidified its political power, while the Polish United Workers' Party (PZPR) under Bolesław Bierut gained firm control over the country, which would remain an independent state within the Soviet sphere of influence. The July Constitution was promulgated on 22 July 1952 and the country officially became the Polish People's Republic (PRL).