Bosanska Krajina (, ) is a geographical region, a subregion of Bosnia, in western Bosnia and Herzegovina. It is enclosed by a number of rivers, namely the Sava (north), Glina (northwest), Vrbanja and Vrbas (east and southeast, respectively). The region is also a historic, economic and cultural entity of Bosnia and Herzegovina, famous for its natural beauties and wildlife diversity. The largest city, and its historical center is Banja Luka. Other cities and towns include Bihać, Bosanska Krupa, Bosanski Petrovac, Bosansko Grahovo, Bužim, Cazin, Drvar, Gradiška, Ključ, Kostajnica, Kozarska Dubica, Laktaši, Mrkonjić Grad, Novi Grad, Prijedor, Sanski Most, Šipovo, Velika Kladuša. Bosanska Krajina is not a formal entity within the structure of Bosnia and Herzegovina; however it has a significant cultural and historical identity that was formed through several historic and economic events. The territory of Bosanska Krajina is currently divided between two entities of Bosnia and Herzegovina: Republika Srpska and the Federation of Bosnia and Herzegovina. Naming During the Medieval Bosnia period, the region of Bosanska Krajina was known as Donji Kraji () and Zapadne Strane (). After the Ottoman conquest of Bosnian Kingdom, and empire's subsequent westward expansion, the region between the Una and Vrbas rivers became known as Krajina () or Bosanska Krajina (). The first recorded usage of the name Bosanska Krajina is in 1594. Also, for the same territory, the exonym Turkish Croatia appeared in German speaking Austria-Hungary in the first decades of the 18th century, and was first used in maps created by the Austro-Hungarian — Ottoman Border Commission, which was mandated by the peace treaty of Karlowitz (1699), and then the peace treaty of Passarowitz (1718), and consisted exclusively of Austrians' and Venetians' military cartographers, and one Croat (Vitezović). In the mid 19th century the term Turkish Croatia, used in some Austrian maps for the Western Balkans, was replaced in favor of region's common name, Bosanska Krajina. Geography Sub-regions (geographical and historical) include: Bihaćka krajina, Cazinska krajina, Potkozarje, Lijevče, etc. History Middle Ages In the 6th century, today's northwestern Bosnia was part of the Roman province of Dalmatia. It fell under the jurisdiction of the Eastern Roman Empire. Shortly thereafter, Eurasian Avars and their Slavic subjects from central-eastern Europe invaded Dalmatia and settled in what is now Bosnia and Herzegovina. In the 7th century the Serbs and Croats formed principalities initially under the Eastern Roman Empire. The region was part of the Duchy