Cyrillic script consonants from the older Glagolitic alphabet for sounds not found in Greek. Tradition holds that Cyrillic and Glagolitic were formalized either by Saints Cyril and Methodius who brought Christianity to the southern Slavs, or by their disciples. Paul Cubberley posits that although Cyril may have codified and expanded Glagolitic, it was his students in the First Bulgarian Empire under Tsar Simeon the Great that developed Cyrillic from the Greek letters in the 890s as a more suitable script for church books. Later Cyrillic spread among other Slavic peoples, as well as among non-Slavic Vlachs. Cyrillic and Glagolitic were used for
Sogdian alphabet also includes several diacritics, which were used inconsistently. It is written from right to left, but by the time it had evolved into its child system, the Old Uyghur alphabet, it had been rotated 90 degrees, written vertically in columns from left to right. Voiced and voiceless fricatives are consistently not distinguished in the script. Aramaic logograms also appear in the script, remnants of adapting the Aramaic alphabet to the Sogdian language. These logograms are used mainly for functional words such as pronouns, articles, prepositions, and conjunctions. The Sogdian alphabet was found inscribed in Panjakent, so we can suppose alphabetisation