The postal history as well as the general history of this Balkan country is complex. The first general stamp issues of Yugoslavia appeared in 1921. They were designed with portraits of King Alexander and his father, King Peter of Serbia. Between 1918 and 1921, stamps of Bosnia and Herzegovina, Croatia and Slavonia, and Slovenia were used. These countries had united in 1918 to form a constitutional monarchy called the Kingdom of the Serbs, Croats, and Slovenes. The country was renamed Yugoslavia in 1929. Some stamps of Yugoslavia are inscribed with the country name in only Cyrillic letters, some in only Latin letters and others in both.