The First Bulgarian Empire was a medieval state that existed in Southeastern Europe between the 7th and 11th centuries AD. It was founded in 680–681 after part of the Bulgars, led by Asparuh, moved south to the northeastern Balkans. There they secured Byzantine recognition of their right to settle south of the Danube by defeating – possibly with the help of local South Slavic tribes – the Byzantine army led by Constantine IV. During the 9th and 10th century, Bulgaria at the height of its power spread from the Danube Bend to the Black Sea and from the Dnieper River to the Adriatic Sea and became an important power in the region competing with the Byzantine Empire.

Church Slavonic, also known as Church Slavic, New Church Slavonic, New Church Slavic or just Slavonic, is the conservative Slavic liturgical language used by the Eastern Orthodox Church in Belarus, Bulgaria, North Macedonia, Montenegro, Poland, Ukraine, Russia, Serbia, the Czech Republic and Slovakia, Slovenia and Croatia. The language appears also in the services of the Russian Orthodox Church Outside of Russia, the American Carpatho-Russian Orthodox Diocese, and occasionally in the services of the Orthodox Church in America.