 The Constitutional Decision on the Sovereignty and Independence of the Republic of Croatia
came into effect on 8 October 1991.The constitution has since been amended several times.The first modern parties in the country developed in the middle of the 19th century, and their agenda and appeal changed, reflecting major social changes, such as the breakup of Austria-Hungary, the Kingdom of Serbs, Croats and Slovenes, dictatorship and social upheavals in the kingdom, World War II, the establishment of Communist rule and the breakup of the SFR Yugoslavia.