On March 4, Bulgaria marks 1,151 years since the foundation of the Bulgarian Orthodox Church. On this day in 870, the Autocephalous Archbishopric of Bulgaria was constituted during the Eight Ecumenical Council in Constantinople.
This happened during the reign of Tsar Boris-Mihail, Baptizer of Bulgaria. The Bulgarian Orthodox Church had a status of Autocephalous Archbishopric until 927 when Constantinople recognized a Bulgarian Patriarchate. The seat of the Bulgarian Patriarchate was the new Bulgarian capital of Preslav.
— bnr.bg
