about the military strength of Croatia and its victory over the Bulgarians. Thomas the Archdeacon mentions Tomislav as a prince in 914, and the church councils of Split, held in 925 and 928. Archbishop Gregory mentions Tomislav's victory over Attila, the Hungarian king. The generally accepted view in historiography is that Tomislav was crowned Croatian king after a successful war with the Hungarians. This happened before 925 when Pope John X referred to him as King of the Croats. Since Thomas the Archdeacon dates the principality of Tomislav to 914, his coronation took place between 914 and 925. The Duvno field with the city of Županjac was in the possession of Croatian kings till the 2nd half of the 13th century when it became the possession of the noble family Šubić. At the end of the 13th and beginning of the 14th century, the Šubić family, with approval from the Pope Boniface VIII, established three dioceses on the territory of the Archdiocese of Split, the Diocese of Šibenik, the Diocese of Makarska and the Diocese of Duvno. The motive for the establishment of those dioceses was to halt the spread of the Bosnian Church and strengthen of Šubićs' influence in the area. The seat of the Diocese of Duvno was the Church of Saint John the Baptist, located in the town of Rog, near the present-day Roško Polje. The bishops of Duvno served mostly as assistants to the archbishop of Split or were only titular bishops. Until the 1320s, Duvno was part of the Kingdom of Croatia, when Stephen II, Ban of Bosnia took the land from Šubićs and incorporated it in the Banate of Bosnia. Duvno became a part of the Western Regions, a province of the Banate of Bosnia, together with Livno and Glamoč. However, the population of the Western Regions didn't identify with the Bosnian Kingdom. After King Tvrtko gave in the territory of Zachlumia westwards from the Neretva river to the Hungarian and Croatian King Louis I in 1357, Duvno became the southwesternmost part of his realm towards the Kingdom of Croatia. A struggle broke out in the village of Kolo, in Duvno, in 1374, due to a division over loyalty between the Bosnian and Croatian-Hungarian King. For this reason, Tvrtko took over the village and gave it to the Semković family from Usora, and their ownership over the village was confirmed by King Dabiša in