Numerous Cyrillic alphabets are based on the Cyrillic script. The early Cyrillic alphabet was developed in the 9th century AD and replaced the earlier Glagolitic script developed by the theologians Cyril and Methodius. Cyrillic is one of the most-used writing systems in the world. The script was created at the Preslav Literary School in the First Bulgarian Empire by the disciples of the two Byzantine brothers Cyril and Methodius, who had previously created the Glagolitic script. Among them were Clement of Ohrid, Naum of Preslav, Constantine of Preslav, Joan Ekzarh, Chernorizets Hrabar, Angelar, Sava and other scholars. It is the basis of alphabets used in various languages, past and present, Slavic origin, and non-Slavic languages influenced by Russian. As of 2011, around 252 million people in Eurasia use it as the official alphabet for their national languages. About half of them are in Russia.