Croats of Bosnia and Herzegovina Dalmatian Croatia formed a united Croatian kingdom, which included Dalmatia and part of Bosnia and Herzegovina, Pannonia (eastern Slavonia and northeastern Bosnia), and Savia (western Slavonia). In 1102 Croatia entered into a union with the Kingdom of Hungary. After this, Bosnia, which was earlier part of the Kingdom of Croatia, started to disassociate with Croatia. At first, Bosnia became a separate principality under Ban Kulin who managed to solidify Bosnian autonomy at the expense of more powerful neighbours, but only in the 14th century did Bosnia become a formidable state. In the 14th century, King Tvrtko I conquered part of
Gradiška, Bosnia and Herzegovina Gradiška, Bosnia and Herzegovina Gradiška (; formerly "Bosanska Gradiška" / Босанска Градишка) is a town and municipality located in northwestern Republika Srpska, an entity of Bosnia and Herzegovina. As of 2013, it has a population of 51,727 inhabitants. It is geographically located in eastern Krajina region, and the town is situated on the Lijevče plain, on the right bank of the Sava river across from Stara Gradiška, Croatia, and about north of Banja Luka. In the Roman period, the "municipium" of Serbinum existed on the location of the present-day town. It was of strategic importance; a port of the Roman