After loosing the First World War Hungary is forced by the "Treaty of Trianon" to render certain terr-itories:

Northern Hungary, Pressburg and Transkarpathia to Czechoslovakia, Transsylvania and the Banat to Romania. Voivodina, Slovonia, Croatia and Wendland were given to Jugoslavia, the western part of Burgenland to Germany/ Austria. Only the eastern part and the city of Sopron remaind to Hungary.