The Kingdom of Croatia, also known as the Kingdom of the Croats, is a medieval kingdom comprising most of what is today Croatia as well as, periodically, parts of Bosnia and Herzegovina in the Balkans.Established in 925, it rules as a sovereign state for almost two centuries.

Its existence is characterized by various conflicts with the Venetians, Bulgarians, Magyars and, occasionally, the Pope.

The goal of promoting the Slavic language in the religious service is initially brought and introduced by the 10th century bishop Gregory of Nin.

In 1102, after a period of time defined as a succession crisis for the Trpimirović Dynasty, the kingdom loses its full sovereignty by the creation of a personal union with the Kingdom of Hungary.