Existed: 29 October 1918 - 1
Independent nations of Bosnia-Herzegovina, most of Croatia and Slovenia and part of Serbia.
On 29th October 1918, various parts of Austria-Hungary declared independence as the State of Slovenes, Croats and Serbs.
These were Bosnia-Herzegovina,
Carniola, Croatia-Slavonia, Dalmatia,
and part of Styria. (Note that the Serbs referred to
in the State's name were those living in Bosnia and other areas, rather
than those in Serbia proper.)
On 24th November 1918, Syrmia (formerly part of the Hungarian land of Croatia-Slavonia) left the State to become part of Serbia.
On 25th November 1918, the former Hungarian land of Vojvodina joined the State.