Originally, upon settling, South Slavs had no writing system, but according to the 9th century Bulgarian scholar Chernorizets Hrabar, they used "lines and cuts". Modern scholars refer to this marking system as the Slavic runes. With Christianity, Slavs of the Balkans also adopted new alphabets: in the west (Croats), the Latin script was used; in the central parts (Serbs), both Greek and Latin; in the east (Bulgarians), only Greek letters. The first attested Slavic script, Glagolitic script, was compiled by the Saint Cyril and Methodius in the 9th century. It is believed that the script reached Serbs quite early, in its both early redactions, Great Moravian and Pannonian, since Methodius was appointed to head the Archbishopric of Sirmium, which also had jurisdiction over the Serbian lands in the hinterland. Methodius was very active in promoting the script among the Slavs, organizing numerous missionary actions with his disciples in the massive effort to spread Christianity among the Slavs.