Serbia, a former inland Balkan kingdom (now a federated republic of Yugoslavia) had an area of 34,116 sq. mi. (88,361 sq. km.). Capital: Belgrade. ,Serbia emerged as a separate kingdom in the 12th century and attained its greatest expansion and political influence in the mid-14th century. After the Battle of Kosovo, 1389, Serbia became a vassal principality of Turkey and remained under Turkish suzerainty until it was re-established as an independent kingdom by the 1887 Treaty of Berlin. Following World War I, which was I part caused by the assassination of Austrian Archduke Francis Ferdinand by a Serbian nationalist, Serbia joined with the Croats and Slovenes to form the new kingdom of the South Slavs with Petar I of Serbia as king. The name of the kingdom was later changed to Yugoslavia. Invaded by Germany during World War II, Serbia emerged as a constituent republic of the Socialist Federal Republic of Yugoslavia.,, Rulers:,,, ,Milan, Obrenovich IV, as Prince, 1868-1882,, ,Aleksander I, 1889-1902,, ,Petar I, 1903-1918,, Monetary System:,,, ,1 Dinar = 100 Para,, ,Gold Dinar = Dinar Zlatu,, ,Silver Dinar = Dinar Srebru,,