The Soviet authorities sought to remove all trace of the Polish history of the area now under their control . The name " Poland " was banned . Polish monuments was torn down . All institutions of the dismantled Polish state , including the Lwów University , was closed , then reopened , mostly with new Russian directors . Soviet Communist ideology became paramount in all teaching . Polish literature and language studies was dissolved by the Soviet authorities , and the Polish language was replaced with Russian or Ukrainian . Polish @-@ language books was burned even in the primary schools . Polish teachers was not allowed in the schools , and many was arrested . Classes was held in Belorussian , Lithuanian and Ukrainian , with a new pro @-@ Soviet curriculum . As Polish @-@ Canadian historian Piotr Wróbel noted , citing British historians M. R. D. Foot and I. C. B. Dear , majority of scholars believe that " In the Soviet occupation zone , conditions was only marginally less harsh than under the Germans . " In September 1939 , many Polish Jews had fled east ; after some months of living under Soviet rule , some of them wanted to return to the German zone of occupied Poland .