On October 8, 927, the Bulgarian Church was declared autocephalous.
The need for a church organization of the Bulgarian lands, independent of the Patriarchate of Constantinople, arose with the conversion of the Bulgarians in 864. Prince Boris I (852-889), through the means of diplomacy and maneuvering between the Eastern and Western Churches, managed to create one. At first, this proved impossible, and he had to come to terms with an archbishop and higher clergy of Greek origin (although directly subordinate to the prince), as well as with divine services in Greek.
At the Preslav National Council convened in 893, along with the election of Simeon as Bulgarian ruler, a decision was made to replace the Greek language with Slavic in divine services. During his reign, Tsar Simeon I (893-927) gradually replaced the Greek higher clergy with Bulgarian and created the Bulgarian Exarchate, which under his successor Tsar Peter I (927-970) grew into a patriarchate. The negotiations between the Tsar and Emperor Romanus Lekapin in 927 resulted in imperial recognition of the Bulgarian ruler's royal title and the canonical elevation of the head of the Bulgarian Church as Patriarch of Bulgaria.
A copy of the decision of the imperial synclite on the recognition of the Bulgarian Patriarchate of October 8 is preserved in the Vatican archives. The first Bulgarian Patriarch was Damian Dorostolski (Drustarski), and his seat was in the capital Veliki Preslav. Subsequently, the patriarchal throne was moved to Drustar.