My great grandparents lived in area within the German Empire where Poles made up 20 to 39 percent of the population, according to a researcher who posted this map on Reddit.
After the Second World War and Germany’s defeat, an amazing swath of land was lost. The surviving Germans were expelled, forced to leave homes & belongings behind.
Today, there are few Germans there. Stalin offered it as compensation for taking Polish lands bordering Russia and absorbing these into the Soviet Union.