Yugoslavia was under control of the Ottoman Empire for an extremely long period of time - from the 1400s until the early 1900s, when the major nations of Serbia Montenegro gained independence. They then fought in a series of Balkan Wars which further freed the Balkans, the future home of Yugoslavia, from Ottoman control.
Serbia and Austria-Hungary were two large powers in the Balkans at this time, and they competed for new nations' spheres of influence. When Austrian heir Arch-Duke Franz Ferdinand arrived in Sarajevo, a Bosnian city, a Serbian nationalist assasainated him, leading into World War I.
Serbia ended up on the winning side of World War I, and gained massive reparations - valued around $400 dollars. They also expanded in Macedonia, and gained international recognition. Following World War I, Serbia formed the Kingdom of Serbs, Croats, and Slovenes, another (antiquidated) name for Yugoslavia.
The King of Serbia became the King of Yugoslavia. King Peter I of Serbia was crowned King of Yugoslavia in 1918, and ruled until his death in 1921. Since 1921, King Alexander I of Yugoslavia has ruled as King of Yugoslavia.
See: Kings of Yugoslavia
While Yugoslavia was originally designed to be relatively democratic, King Alexander's rise to power in 1921, and his subsequent reign, has all but eliminated democracy in Yugoslavia. He is a practically a military dictator, and is extremely unpopular in Macedonia.
A relatively new constitution, the Constitution of 1931, was enacted by King Alexander, and gives the King full executive powers. This was extremely unpopular with all Yugoslavians (save for the Serbs), and the Croats threatened a war to leave Yugoslavia. The King has promised to correct this, and plans for a new democracy are underway.
The Yugoslav economy is based around agriculture. Over three-fourths of Yugoslavs work as farmers, with an even balance between commercial and substenance farming. The remainder of the work force are either in the military or work in factories in large cities such as Belgrade or Zagreb. King Alexander has promised to improve the Yugoslavian economy.
The official military of Yugoslavia is divided into three branches - the Yugoslav Royal Army, the Yugoslav Naval Command, and the Yugoslav Air Defence Forces. These three branches comprise the Royal Yugoslav Armed Forces.
Each branch can operate independently, but can also work through the commander - the highest ranking member of the Yugoslav Armed Forces, to organize a joint attack.
The Royal Yugoslav Armed Forces have never been in a war, however many Balkan armies have been in large scale conflicts. Among these are the Balkan Wars and World War I.