succeeded_by Croatia Slovenia Serbia Bosnia and Herzegovina Macedonia Montenegro [Former] Yugoslavia A former state. The six countries that were once part of Yugoslavia are Bosnia-Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia. Democratic Federation of Yugoslavia Federal People's Republic of Yugoslavia GAZ GAZ:00052663 GAZ:00052663 Jugoslavia Socialist Federal Republic of Yugoslavia begin_date: 1943-11-29. end_date: 1991-06-25. Previous to 1943: Kingdom of Yugoslavia, begins_in: 1918-12-01; end_date: 1941-04_17. Croatia Slovenia Serbia Bosnia and Herzegovina Macedonia Montenegro [Former] Yugoslavia A former state. The six countries that were once part of Yugoslavia are Bosnia-Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia. Democratic Federation of Yugoslavia Federal People's Republic of Yugoslavia GAZ GAZ:00052663 GAZ:00052663 Jugoslavia Socialist Federal Republic of Yugoslavia begin_date: 1943-11-29. end_date: 1991-06-25. Previous to 1943: Kingdom of Yugoslavia, begins_in: 1918-12-01; end_date: 1941-04_17.