In 1939 , the Molotov – Ribbentrop Pact between Nazi Germany and the Soviet Union resulted in the invasion of Poland by the two powers and its division between them . Slonim was in the area designated by the Pact to fall within the Soviet sphere of influence . The Soviets placed that area within the Byelorussian SSR . Two years later , Germany invaded the Soviets ( Operation Barbarossa ) and Slonim was captured . The Słonim Jews were herded into the Słonim Ghetto set up at the Na Wyspie neighbourhood across the bridge on the Szczara River . Soon thereafter , 70 % of Slonim 's Jews had been killed by the '' Einsatzgruppen '' , including 9,000 on 14 November 1941 . The second mass murder of 8,000 Jews took place in 1942 . In 1944 , on the insistence of Joseph Stalin in Yalta the Soviet Union retained possession of this part of the former Poland , as agreed between the Allies . Polish population was forcibly resettled back to new Poland before the end of 1946 . After the breakup of the Soviet Union , Slonim became part of an independent state of Belarus
in Yalta
Yalta Conference
Slonim