The Bulgarian monarchs used the titles kanasubigi, khan, knyaz and tsar (emperor).
During the Third Bulgarian State accession was marked by an oath on the constitution.
Eastern Orthodox Christianity entered Bulgaria during the reign of Prince Boris I.
Prince Simeon I was the first Bulgarian ruler to be crowned in the Christian Faith.
Halfway through his reign, Simeon assumed the title of Tsar (Emperor) of Bulgarians and the Romans.,[1] having prior to that been styled Knyaz.