Herzegovina, because of its geographic position and terrain, was probably one of the last areas to go through this process, which presumably originated from the urban centers along the Dalmatian coast. Thus, Slavic Bosnian tribes remained pagans for a longer time, and finally converted to Christianity.
The principalities of Serbia and Croatia split control of Bosnia and Herzegovina in the 9th and 10th century, but by the High Middle Ages political circumstance led to the area being contested between the Kingdom of Hungary and the Byzantine Empire. Following another shift of power between the two in the early 12th century, Bosnia found itself outside the control of both and emerged as an independent state under the rule of local bans.
The first Bosnian monarch was Ban Borić. The second was Ban Kulin whose rule marked the start of a controversy with the Bosnian Church, because he allowed an indigenous Bogomilism sect considered heretical by the Roman Catholic Church. In response to Hungarian attempts to use church politics regarding the issue as a way to reclaim sovereignty over Bosnia, Kulin held a council of local church leaders to renounce the heresy and embraced Catholicism in 1203. Despite this, Hungarian ambitions remained unchanged long after Kulin's death in 1204, waning only after an unsuccessful invasion in 1254.
Bosnian history from then until the early 14th century was marked by a power struggle between the Šubić and Kotromanić families. This conflict came to an end in 1322, when Stephen II Kotromanić became Ban. By the time of his death in 1353, he was successful in annexing territories to the north and west, as well as Zahumlje and parts of Dalmatia. He was succeeded by his nephew Tvrtko who, following a prolonged struggle with nobility and inter-family strife, gained full control of the country in 1367. Tvrtko crowned himself in 1377 as Stephen Tvrtko I the King of "Serbia, Bosnia, Pomorje, and the Western lands".
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