The Bulgarians were the first people to use the Cyrillic alphabet immediately after its inception in the 9th century. The invention of the Cyrillic alphabet is attributed traditionally to Sts. Cyril and Methodius, Byzantine missionaries, whose purpose was to translate the New Testament into the then-common language of the Slavic peoples. However, the two brothers created the Glagolithic alphabet, not the Cyrillic. It was their disciple Saint Climent, the Bulgarian archbishop of the town of Ohrid, who invented the simpler Cyrillic alphabet and named it in honor of his teacher. The Cyrillic alphabet, like the Roman, stems from the Greek; additional characters, however, were devised to represent Slavic sounds that had no Greek equivalents. From Bulgaria, the cultural center of the medieval Slavs, the Cyrillic alphabet spread to the neighboring countries, such as Serbia, and to the far-lying Eastern Slavs, the Russians, the Ukrainians, and the Belarussians. The Cyrillic alphabet, in various forms, is used currently in Russian, Ukrainian, Belarussian, Serbian, and Bulgarian, but not in Polish, Czech, Slovak, or Slovenian, which are written in modified Roman alphabets.
Since Sts. Cyril and Methodius were from the city of Thessaloniki, they chose the dialect of the Bulgarian Slavic tribes residing in the area as the foundation for the creation of the new alphabet. Hence the language written in this alphabet is known as Old Bulgarian, Old Slavonic or Old Church Slavonic and is still used as a liturgical language in Eastern Orthodox Slavic churches. For most of the middle ages Old Bulgarian was the language of the ecclesiastical literature and of official and diplomatic documents of the Eastern Orthodox Slavs. Click here to learn more about the history and development of the Bulgarian language.
The Modern Bulgarian Period started in the 15th century, but the modern literary language, which is quite different from Old Bulgarian, formed only during the 19th century. Until that time St. Climent's original Cyrillic alphabet, containing 44 letters for 44 sounds, had been used; however, by the 19th century the Bulgarian sound system had changed dramatically and contained fewer sounds. That necessitated an alphabet reform which reduced the number of letters used from 44 to 32; this modified alphabet was used until the Orthographic reform of 1945.