The best known historical proponent of anti-Serb sentiment was the 19th- and 20th-century Croatian Party of Rights. The most extreme elements of this party became the Ustasha in the Kingdom of Yugoslavia, a Croatian fascist organization that came to power during World War II and instituted racial laws that specifically targeted Serbs, Jews, Roma and dissidents. This culminated in the genocide of Serbs and members of other minority groups that lived in the Independent State of Croatia (1941–1945).