The Kingdom of Yugoslavia (formerly the Kingdom of Serbs, Croats and Slovenes) was created by the unification of the Kingdom of Serbia (which included Montenegro and parts of Macedonia) and the temporary nations of Slovenia and Croatia on 1 December 1918. Until 1929, the Kingdom of Serbs, Croats and Slovenes was a parliamentary monarchy, but King Alexander I decided to abolish the old constitution and installed himself as an absolute ruler. He renamed the country the Kingdom of Yugoslavia in October of 1929.