During the reign of Boris I (r. 852–889) Bulgaria underwent major changes — the Christianization of the country and the admission of the disciples of Saints Cyril and Methodius, which marked the beginning of the creation and consolidation of the medieval Bulgarian literature and alphabet.
Following intense negotiations with the Papacy in Rome and the Ecumenical Patriarchate of Constantinople, Bulgaria converted to Eastern Orthodox Christianity, which caused discontent among part of the nobility who directly associated the new religion with the Byzantine Empire and feared that the country would fall under Byzantine influence.

During the Council of Preslav in 893, assembled after the unsuccessful attempt of Boris I's eldest son Vladimir-Rasate (r. 889–893) to restore the traditional Bulgar religion, Tengriism, it was decided that Old Bulgarian would replace Greek as the language of the church and the Byzantine clergy would be banished and replaced with Bulgarians.
The Council sealed Boris I's ambitions to secure the cultural and religious independence from the Byzantine Empire and calmed down the concerns among the nobility.
It was also decided that his third son Simeon, born after the Christianization and called the "child of peace", would become the next Prince of Bulgaria.
These events brought an end to the Byzantine hopes to exert influence over the newly Christianized country.
During the reign of Boris I (r. 852–889) Bulgaria underwent major changes — the Christianization of the country and the admission of the disciples of Saints Cyril and Methodius, which marked the beginning of the creation and consolidation of the medieval Bulgarian literature and alphabet. Following intense negotiations with the Papacy in Rome and the Ecumenical Patriarchate of Constantinople, Bulgaria converted to Eastern Orthodox Christianity, which caused discontent among part of the nobility who directly associated the new religion with the Byzantine Empire and feared that the country would fall under Byzantine influence.
During the Council of Preslav in 893, assembled after the unsuccessful attempt of Boris I's eldest son Vladimir-Rasate (r. 889–893) to restore the traditional Bulgar religion, Tengriism, it was decided that Old Bulgarian would replace Greek as the language of the church and the Byzantine clergy would be banished and replaced with Bulgarians. The Council sealed Boris I's ambitions to secure the cultural and religious independence from the Byzantine Empire and calmed down the concerns among the nobility. It was also decided that his third son Simeon, born after the Christianization and called the "child of peace", would become the next Prince of Bulgaria. These events brought an end to the Byzantine hopes to exert influence over the newly Christianized country.
Byzantine–Bulgarian war of 894–896