Usora (, ) was important zemlja (; feudalna oblast ) of the medieval Bosnian state, first banate and later kingdom, although it also had some periods outside its jurisdiction and royal authority, when it was connected with neighboring banates of Slavonia, or Mačva at times. The administrative seat of this zemlja was Srebrenik, which also served as residence for its rulers for entire period of existence of the medieval Bosnian state. It took its name from the river Usora. Ethimology The name of the land of Usora derives from the eponymous river, which runs through its territories for approximately 80 kilometers, in direction south-southwest to north-northeast, and spills into the river Bosna just south of town of Doboj. Geography and location Usora was the northernmost Bosnian land (zemlja), occupying very fertile Pannonian Plain, and its geographical location roughly correspond to modern-day Northern Bosnia gravitating toward Posavina. 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 land of Usora had many strong fortresses and towns on its territory, the most famous ones being Doboj (13th century), Srebrenik (1333), Dobor fortress (1387), Glaž (12th century), Soko fortress (14th century), Tešanj (14th century), Modriča town (13th century), and Maglaj (15th century). History The region of Usora was first mentioned in a bull (decree) dated 20 July 1244 by the King Bela IV of Hungary, 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 referring to Usora, Sou to Soli, and Olfeld to Donji Kraji). Although it was nominally included into the Hungarian Crown Lands, the Banate of Bosnia was a de facto independent state for the course of its existence, including Usora, which under Bosnia always retained certain amount of autonomy. Battles Notable battles include Battle of Srebrenik (1363), Battle of Dobor (1394) and (1408), and the Battle of Doboj (1415). During its history, this zemlja had been separated several times from the Banate of Bosnia and later Bosnian Kingdom, mostly by the Kingdom of Hungary which appointed rulers of this region, and sometimes attached it to Slavonian Banate. Prominent families, such as Babonići had estates there while the territories were part of