Cyril and Methodius

Saints Cyril and Methodius were brothers and 9th century Christian missionaries. They Christianized the Slavic peoples of the Danube. They influenced the culture and religion of all Slavic peoples. They received the title "Apostles to the Slavs".
Secular lives.
The brothers were both born in Thessalonica. Methodios was born and died in 885. Cyril was born and died (under his adopted name Constantine) in 869. Cyril was educated at the university at Constantinople under Photios I of Constantinople. He later taught there when he replaced Photios. Methodios became governor of the province of Opsikion at about the same time.
Missionaries.
In 861 the Byzantine Emperor Michael III sent the two brothers to convert the Khazars to Christianity. They continued their religious conversion of the Tatars along the Black Sea for two years. Afterwards the Emperor Michael sent them to Moravia as missionaries. They taught in the Slavic languages and translated the Scriptures into Slavonic. Cyril invented an alphabet called the Glagolitic alphabet. This became the basis for the Cyrillic alphabet. Old Church Slavonic was written in Cyrillic and Glagolitic.