The verigar, designed by Ivan Vavpotič for the state’s only postal stamp issue, became one of the symbols of the short-lived State of Slovenes, Croats, and Serbs (Source wikipedia)

29th October- 1st December 1918: The State of Slovenes, Croats and Serbs

The first state which can be seen as the base for “Yugoslavia” was the shortly exisiting state of “State of Slovenes, Croats, and Serbs”. In Slovenian, the State was known as Drzava Slovencev, Hrvatov in Srbov; in Serbian and Croatian as Drzava Slovenaca, Hrvata i Srba (Cyrillic: Држава Словенаца, Хрвата и Срба).

The state was officially formed on 29 October 1918. On 1 December 1918, the National Council joined the state with the Kingdom of Serbia (which already had merged with the Kingdom of Montenegro) to form the Kingdom of Serbs, Croats, and Slovenes.

(source Wikipedia: State of Slovenes,Croats and Serbs)

1st December 1918-1929: Kingdom of Serbs, Croats and Slovenes

The Kingdom of Yugoslavia (Serbo-Croat and SloveneKraljevina JugoslavijaCyrillic script: Краљевина Југославија) was a kingdom stretching from the Western Balkans to Central Europewhich existed during the often-tumultuous interwar era of 1918-1941. It was formed in 1918 when merging the newly formed State of Slovenes, Croats and Serbs with the formerly independent Kingdom of Serbia. The Kingdom of Montenegro had passed to Serbian rule days earlier, while the regions of KosovoVojvodinaand Macedonia were parts of Serbia prior to the unification. For its first eleven years of existence it was officially called Kingdom of Serbs, Croats and Slovenes, but the term Yugoslavia was its colloquial name from the very beginning. On 17 April 1941, Yugoslavia fell prey to Nazi occupation and was reorganised into four provinces under foreign rule; a royal government-in-exile, recognized by the Allied powers, was established in London. The monarchy was officially abolished on 29 November 1945, when the Federal People’s Republic of Yugoslavia was established following the Belgrade Offensive.

Source: en.wikipedia.org/wiki/Kingdom_of_Serbs,_Croats,_and_Slovenes

3th October 1929: Kingdom of Yugoslavia

The 3th October 1929, the Kingdom of Serbs, Croats and Slovenes was renamed to “the Kingdom of Yugoslavia”.

On the 9th October 1934 King Alexander I of Yugoslavia was killed  in Marseille (France).  It was one of the first assassinations captured on film; the shooting occurred straight in front of the cameraman, who was only feet away at the time. The cameraman captured not merely the assassination but the immediate aftermath; the body of the chauffeur (who had been killed instantly) became jammed against the brakes of the car, allowing the cameraman to continue filming from within inches of the King for a number of minutes afterwards.

See the video on youtube:
http://www.youtube.com/watch?v=B8ZLj7x1vN4