Yugoslavia was a city.
Croatia became merged with Serbia and Slovenia to form the nation of Yugoslavia in 1918 . Yugoslavia ( Jugoslavija / Југославија , Jugoslavija , Југославија ) was a country in Southeast Europe during most of the 20th century . The country was named after the South Slavic peoples and constituted their first union , following centuries in which the territories had been part of the Ottoman Empire and Austria-Hungary . In 1963 , the country was renamed again as the Socialist Federal Republic of Yugoslavia ( SFRY ) . The constituent six socialist republics that made up the country were the SR Bosnia and Herzegovina , SR Croatia , SR Macedonia , SR Montenegro , SR Serbia , and SR Slovenia .