Pope Stephen V exiled the disciples of the two brothers from Great Moravia in 885. They fled to the First Bulgarian Empire, where they were welcomed and commissioned to establish theological schools. There they and scholar Saint Clement of Ohrid devised the Cyrillic script on the basis of the Glagolitic. Cyrillic gradually replaced Glagolitic as the alphabet of the Old Church Slavonic language, which became the official language of the Bulgarian Empire and later spread to the Eastern Slav lands of Kievan Rus'. Cyrillic eventually spread throughout most of the Slavic world to become the standard alphabet in the Eastern Orthodox Slavic countries. Hence, Cyril and Methodius' efforts also paved the way for the spread of Christianity throughout Eastern Europe.