 Complete the following phrase:  During the subsequent Potsdam Conference in JulyAugust 1945, the three major Allies ratified the colossal westerly shift of the Polish frontier and approved its new territory between the OderNeisse 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 