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
Croats of Bosnia and Herzegovina and Fojnica. Around 30% of the present-day territory of Bosnia and Herzegovina become part of Banovina of Croatia. Those parts had a Croatian majority. Creation of Banovina of Croatia was one of the solutions to the ""Croatian issue"". After the collapse of Yugoslavia amidst German and Italian invasion in April 1941, the Axis puppet state which encompassed the entire Bosnia and Herzegovina, Independent State of Croatia (NDH) under the radical Croat nationalist ustaša regime was established. Bosnian Croats were divided, as some supported NDH, some actively opposed it by joining or supporting the Yugoslav Partisans, while others chose to wait,