It should have been:
Molotov-Ribbentrop Pact. Partition of Poland: Germany and the Soviet Union agreed to partition Poland among themselves. The western part of Poland was to be annexed by Germany, and the eastern part by the Soviet Union.
What's happened.
The partition of Poland after World War II was the result of decisions taken at the Yalta Conference (February 1945) and the Potsdam Conference (July-August 1945). These conferences were held by the leaders of the Allied powers: the USA, the USSR and Great Britain.