Not a distinctive rite, but the liturgical language used in the Byzantine Rite by Catholic and Orthodox Russians, Ruthenians, Bulgars, Serbs, and others. About A.D. 866, Sts. Cyril and Methodius translated the liturgy into Old Slavonic, the language of the people in Moravia and Pannonia, and invented a new alphabet (Cyrillic) for their Slavic converts. Pope Adrian II approved the action. The Roman liturgy in Old (Southern) Slavonic dates in some territories from about the eleventh century and is still in use in Dalmatia and Croatia (Yugoslavia). The introduction of the vernacular in the liturgy since the Second Vatican Council has naturally affected the use of Slavonic among Catholics.