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. (November 2018)
The Kingdom of Croatia (Croatian: Kraljevina Hrvatska, Latin: Regnum Croatiae), or Croatian Kingdom (Croatian: Hrvatsko Kraljevstvo), was a medieval kingdom in Central Europe comprising most of what is today Croatia (without western Istria and some Dalmatian coastal cities), as well as most of the modern-day Bosnia and Herzegovina. Part of the Croatian Kingdom period ruled by ethnic dynasties, the Kingdom existed as a sovereign state for nearly two centuries. Its existence was characterized by various conflicts and periods of peace or alliance with the Bulgarians, Byzantines, Hungarians, and competition with Venice for control over the eastern Adriatic coast. The goal of promoting the Croatian language in the religious service was initially brought and introduced by the 10th century bishop Gregory of Nin, which resulted in a conflict with the Pope, later to be put down by him. In the second half of the 11th century Croatia managed to secure most coastal cities of Dalmatia with the collapse of Byzantine control over them. During this time the kingdom reached its peak under the rule of kings Peter Krešimir IV (1058–1074) and Demetrius Zvonimir (1075–1089).
The state was ruled mostly by the Trpimirović dynasty until 1091. At that point the realm experienced a succession crisis and after a decade of conflicts for the throne and the aftermath of the Battle of Gvozd Mountain, the crown passed to the Árpád dynasty with the coronation of King Coloman of Hungary as "King of Croatia and Dalmatia" in Biograd in 1102, uniting the two kingdoms under one crown. The precise terms of the relationship between the two realms became a matter of dispute in the 19th century. The nature of the relationship varied through time, Croatia retained a large degree of internal autonomy overall, while the real power rested in the hands of the local nobility. Modern Croatian and Hungarian historiographies mostly view the relations between Kingdom of Croatia and Kingdom of Hungary from 1102 as a form of a personal union of two internally autonomous kingdoms united by a common king.
The first official name of the country was "Kingdom of the Croats" (Latin: Regnum Croatorum; Croatian: Kraljevstvo Hrvata), but over the course of time the name "Kingdom of Croatia" (Regnum Croatiae; Kraljevina Hrvatska) prevailed in use. From 1060, when Peter Krešimir IV gained control over coastal cities of the Theme of Dalmatia, earlier under the Byzantine Empire, the official and diplomatic name of the kingdom was "Kingdom of Croatia and Dalmatia" (Regnum Croatiae et Dalmatiae; Kraljevina Hrvatska i Dalmacija). Such form of the name lasted until the death of King Stephen II in 1091.