The Bulgarian monarchs used the titles kanasubigi, khan, knyaz and tsar (emperor). When acceding to the throne in the First and Second Bulgarian Empire the occasion was marked with a coronation, conducted by the Bulgarian Orthodox Church. 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. He converted to Orthodoxy in 864. His godfather was Emperor Michael III and Boris accepted the name Michael as his Christian name. His title was changed from the pagan Kanas to the Christian Knyas.
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.[2] He was recognised and crowned by Patriarch Nicholas I Mystikos in 913 as Emperor of the Bulgarians by Patriarch Nicholas in the Blachernae Palace[3] [4] outside the city walls of Constantinople.
The rulers of the Second Bulgarian Empire were crowned in Tarnovo.
The Bulgarian rulers of the Third Bulgarian Tsardom were not crowned.