After the Bolsheviks took power in Russia, some of the closest study of the new Communist regime and Soviet state was conducted by Polish scholars, whose country had a long history of troubled relations with Russia. Polish scholars had long been studying the Tsarist regime, but the advent of Soviet rule forced major adjustments. Some of the literature that emerged in Poland about the Soviet Union was perceptive, but other works were warped by anti-Semitism and an obsession with alleged Bolshevik-Judeo conspiracies. By the time of World War II, a substantial body of expertise about the USSR had accumulated in Poland. The war and the subsequent establishment of Soviet hegemony largely brought an end to this tradition, which could not truly be revived until after 1989.