In terms of religion, Byzantine Greek Macedonia is also significant as being the home of Saints Cyril and Methodius, two Greek brothers from Thessaloniki (Salonika) who were sent on state-sponsored missions to proselytize among the Slavs of the Balkans and east-central Europe. This involved Cyril and Methodius having to translate the Christian Bible into the Slavs' own language, for which they invented an alphabet that became known as Old Church Slavonic. In the process, this cemented the Greek brothers' status as the pioneers of Slavic literature and those who first introduced Byzantine civilization and Orthodox Christianity to the hitherto illiterate and pagan Slavs.