The Cyrillic script is a writing system used for various languages across Eurasia and is used as the national script in various Slavic, Turkic, Mongolic, and Iranic-speaking countries in Eastern Europe, the Caucasus, Central Asia and Northern Asia. In the 9th century AD the Bulgarian Tsar Simeon I the Great, following the cultural and political course of his father Boris I, commissioned a new script, the Early Cyrillic alphabet, to be made at the Preslav Literary School in the First Bulgarian Empire, which would replace the Glagolitic script, produced earlier by Saints Cyril and Methodius and the same disciples that created the new Slavic script in Bulgaria. The usage of the Cyrillic script in Bulgaria was made official in 893. The new script became the basis of alphabets used in various languages, especially those of Orthodox Slavic origin, and non-Slavic languages influenced by Russian. For centuries Cyrillic was used by Catholic and Muslim Slavs too.