The
Kingdom of Croatia (; ) was a medieval kingdom in
Central Europe comprising most of what is today
Croatia (without most of
Istria and some
Dalmatian coastal cities), as well as parts of modern-day
Bosnia and Herzegovina. 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
Slavic 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).