Administrative divisions of Yugoslavia
Yugoslavia had various administrative divisions in different time periods. 1918–1922. From 1918 to 1922, the Kingdom of Serbs, Croats, and Slovenes continued to be subdivided into the pre–World War I divisions (districts, counties and kingdoms) of the Habsburg monarchy and the formerly independent Balkan kingdoms of the Serbia and the Montenegro. The provinces ("pokrajine") were: 1922–1929. The Vidovdan Constitution of 1921 established the Kingdom of Serbs, Croats, and Slovenes as a unitary state and, in 1922, 33 new administrative "oblasts" (provinces) ruled from the center were instituted: 1929–1941. From 1929, the Kingdom of the Serbs , Croats and Slovenes was renamed Kingdom of Yugoslavia and was subdivided into nine new provinces called "banovinas". Their borders were intentionally drawn so that they would not correspond either to boundaries between ethnic groups, or to pre–World War I imperial borders. They were named after various geographic features, mostly rivers. Slight changes to their borders were made in 1931 with the new Yugoslav Constitution. The banovinas were as follow: As an accommodation to Yugoslav Croats, the Banovina of Croatia ("Banovina Hrvatska") was formed in 1939 from a merger of the Littoral (Maritime) and Sava Banovinas, with some additional territory  from the Vrbas and Zeta Banovinas. Like Sava, its capital was Zagreb. 1941–1944. During World War II, Kingdom of Yugoslavia was occupied and partitioned by the Axis powers and was divided into 3 Axis puppet states: Other parts of the Kingdom of Yugoslavia were occupied by German, Italian, Hungarian, Bulgarian and Albanian Axis troops. 1945–1992. Socialist Federal Republic of Yugoslavia was divided into 6 republics and two autonomous provinces: Federal subdivisions were further down divided into cities and srezs, second of which were constituted by several municipalities. In 1955 srez level units were abolished with only cities and municipalities remaining  in place. SR Croatia 1945–1992. In the Socialist Republic of Croatia srez level units were known as kotars. Socialist epoch was a period of numerous reforms and changes in administrative organization. 1947 law divided Croatia into 81 kotar, 18 cities and 2278 local people's boards/units. In 1949 the Republic was divided into 6 oblasts (Bjelovar, Osijek, Karlovac, Rijeka, Split and Zagreb) and the City of Zagreb which remained in place only until 1951. In 1952 municipalities (općinas) were reintroduced alongside kotara and cities leading to significant reform in 1955 when the republic was divided into 299 municipalities and  27 kotars (decreasing the previous number of 737 municipalities and 96 kotars). Number of municipalities was further decreased in following years reaching the number of 111 municipalities in 1963. Kotars were abolished in 1967 while the new republican constitution of 1974 requested municipalities to join into Communities of Municipalities with participation becoming voluntary in 1988. Following the first multi party elections and before formal independence administrative division turned into prominent issue leading to the Croatian War of Independence. 1990 construction introduced counties of Croatia and formally reintroduced (in practice never implemented) kotars in the case of Autonomous Kotar of Knin  and Autonomous Kotar of Glina. The new counties were effectively defined and introduced only in 1992. Successor states. After dissolution of Yugoslavia, in 1991–1992, five successor states were formed: