Complex sentence: By the Carinthian Plebiscite in October 1920, the main area of the duchy formed the Austrian state of Carinthia, a small southeastern part (the present-day region of Slovenian Carinthia) was included into the newly created Kingdom of Serbs, Croats and Slovenes.
Split into simpler sentences: By the Carinthian Plebiscite in October 1920, the main area of the duchy formed the Austrian state of Carinthia. A small southeastern part (the present-day region of Slovenian Carinthia) was included in the newly created Kingdom of Serbs, Croats and Slovenes.