In 1941 , Syrmia was occupied by the World War II Axis powers and its entire territory was ceded to the Independent State of Croatia , a Nazi puppet state . The fascist Ustashe regime systematically murdered Serbs ( as part of the Genocide of the Serbs ) , Jews ( The Holocaust ) , Roma ( The Porajmos ) , and some political dissidents . In 1945 , with the creation of new borders , eastern Syrmia became part of Vojvodina , while western Syrmia became part of Croatia
Genocide of the Serbs
Persecution of Serbs in the Independent State of Croatia
Syrmia