The game reached Bosnia and Herzegovina at the start of the 20th century, with Sarajevo (in 1903) and Mostar (in 1905) being the first cities to embrace it. Banja Luka, Tuzla, Zenica and Bihać were next along with numerous smaller towns as the sport spread. The country was under Austro-Hungarian rule when official competition began in 1908, though these activities were on a small scale within each territory. At the outbreak of World War I, there were five clubs in Sarajevo, four based on religious and ethnic affiliation: SAŠK as Bosnian Croatian, Slavija affiliated to Bosnian Serbs, Bosnian Muslim's Đerzelez (also known as "Sarajevski") and Makabi Sarajevo (also known as "Barkohba") as Bosnian Jewish club; while only multi-ethnic was worker's club RŠD Hajduk. Along with Sarajevo-based clubs there were approximately 20 outside the capital. The creation of the Kingdom of Yugoslavia post 1918 brought an increase in the number of leagues, and soon a domestic national championship was organised featuring two teams from Bosnia and Herzegovina, the champions of Banja Luka Football Subassociation and Sarajevo Football Subassociation. In 1920, the direct predecessor of the football association of Bosnia-Herzegovina was founded as the Sarajevo football subassociation. The unified championship ran until 1939/40.