About:Serbo-Croatian, or Serbo-Croat, less commonly Bosnian/Croatian/Serbian (BCS), is a South Slavic language and the primary language of Serbia, Croatia, Bosnia and Herzegovina, Montenegro. It is a pluricentric language with four mutually intelligible standard varieties. The language was standardized in the mid-19th century, decades before a Yugoslav state was established. There were dual Serbian and Croatian standards from the very beginning. Croats and Serbs differ in religion and were historically part of separate empires. They adopted slightly different literary forms as their respective standards, though based on the same Eastern Herzegovinian subdialect of the Shtokavian dialect. Since independence, Bosnian has likewise been established as an official standard in Bosnia and Herzegovina, and there is an ongoing movement to codify a separate Montenegrin standard. Serbo-Croatian thus generally goes by the ethnic names Serbian, Croatian, Bosnian, and sometimes Montenegrin. In the 20th century, Serbo-Croatian served as the official language of the Kingdom of Yugoslavia (when it was called "Yugoslavian"), and later as one of the official languages of the Socialist Federal Republic of Yugoslavia. The dissolution of Yugoslavia affected language attitudes, so that social conceptions of the language separated on ethnic and political lines.