The Glagolitic alphabet, also known as Glagolitsa, is the oldest known Slavic alphabet. Although popularly attributed to Saints Cyril and Methodius and the introduction of Christianity, the origin of the Glagolitic alphabet is obscure.
The medieval text "Pannonian Life of Constantine" records that the Slavs were already literate at the time of Cyril's mission: "during a mission to the Crimea in 860, he was shown a Gospel and Psalter written in Rus letters. St Cyril is reported not to have seen these before, but to have learnt to read them surprisingly quickly." (Cubberley, 1996)