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The region of Usora was first mentioned in a bull (decree) by King Bela IV of Hungary dated 20 July 1244, in which he assigned some properties to the Bishop of Bosnia, naming the territories: quod episeopus (Bosnensis) et capitulum decimas in Vozora, in Sou, in Olfeld et in aliis supis ... habeant et percipiant (Vozora meaning Usora, Sou meaning Soli, and Olfeld meaning Donji Kraji).
Its territory stretched roughly from the area of Kulaši and Prnjavor to its west, to Srebrenik and Lukavac to its east, the river Sava to its north and Žepče to its south. The Banate of Usora had many strong fortresses and cities on its territory, the most famous ones being Doboj (12th/13th century), Srebrenik (1333), Dobor (1387), Glaz (12th century), Soko (14th century), Tešanj (14th century), Modrić (14th century), and Maglaj (15th century). Also, due to its geographical location (Pannonian plateau) as the northernmost Bosnian land and its richness, Usora was, more often than not, a most common battleground between the Bosnian kingdom and the Kingdom of Hungary. The most famous battles include Battle of Srebrenik (1363), Battle of Dobor (1394 and 1408), and the Battle of Doboj (1415). Several times this duchy/banate had been separated from the rest of the Bosnian Kingdom (and attached to Hungary, banate of Slavonia) temporarily, only to be reunited once again.
- Vjekoslav Klaić (March 1880). "Topografske sitnice (I)". Journal of the Zagreb Archaeological Museum (in Croatian) (Archaeological Museum, Zagreb) 2 (1): 68. ISSN 0350-7165. Retrieved 2012-09-02.
- Pavo Živković, Marija Brandić (May 2007). "Usora i Soli u prva dva stoljeća turske prevlasti". Povijesni zbornik: godišnjak za kulturu i povijesno nasljeđe (in Croatian) (Faculty of Philosophy, University of Osijek) 1 (1-2): 58–59. ISSN 1846-3819. Retrieved 2012-09-02.