Did Cyril and Methodius create a new language?

Around 860 CE, the brothers Cyril and Methodius from Thessaloniki created a new alphabet and a written language for the Slavs. The alphabet has later come to be called Glagolitic, and the language is now known as Old Church Slavonic, or OCS for short. Since Glagolitic had no obvious model among the alphabets of the time, and even the earliest OCS texts made use of highly complex stylistic and syntactic devices that certainly did not directly reflect any spoken Slavic dialect, Cyril and Methodius’ work seems to have involved an unusually high amount of language planning, even language invention. However, a closer looks reveals that the creation of OCS was not a process different from the development other written languages, including some that Cyril and Methodius knew of. The specific feature of OCS was its portability: from Cyril and Methodius’ local project around Thessaloniki, it quickly developed into a full-fledged liturgical language in Moravia, then into the official language of the First Bulgarian State, further into the liturgical language of the Roman Catholic Croats, and most notably – in a variety written with the new Bulgarian alphabet called Cyrillic – into an interethnic carrier of culture among most Orthodox peoples.Non peer reviewe