Polish population transfers (1944-1946) were a big movement of people during and after World War 2. Back then, Poland was divided between two different countries: the USSR (now Russia) and Nazi Germany (now Germany). During the war, huge numbers of people were forced to leave their homes and move to other parts of Poland. After the war ended in 1945, the two countries wanted to switch the people living in their countries, so they agreed to do big transfers of people. That means some Polish people living in the USSR had to go live in Germany, and some Germans living in Germany had to go live in the USSR. This was a big and difficult event for everyone involved, and it meant a lot of people had to leave their homes and move somewhere new.