During the Greek Civil War (1944–1949), many Macedonians (regardless of ethnicity) participated in the ELAS resistance movement organized by the Communist Party of Greece. ELAS and Yugoslavia were on good terms until 1949, when they split due to Tito's lack of allegiance to Joseph Stalin (cf. Cominform). After the end of the war, the ELAS fighters who took refuge in southern Yugoslavia and Bulgaria were not all permitted by Greece to return: only those who considered themselves Greeks were allowed, whereas who considered themselves Bulgarian or Macedonian Slavs were barred. These events also contributed to the bad state of Yugoslav-Greek relations in the Macedonia region.