In the Middle Ages, Old Nubian was the principal language of the Sudan and the southern part of Egypt. The direct ancestor of the Nubian still spoken in that area, it is the only indigenous African language whose development we can follow for over a millennium. The corpus of Old Nubian, which occupies fewer than one hundred pages of continuously printed text, extends from the eighth to the fifteenth century of our era, though most of the material is from the tenth to the twelfth. About half of the texts are of religious content, comprising translations of the Greek New Testament, the Septuagint and other Christian writings; the rest are documentary, consisting of public contracts, private letters and similar material. Belonging to the Nilo-Saharan language family, Old Nubian is written in a modified form of the Greek uncial alphabet, with extra characters taken from Coptic and Meroitic. The general characteristics of the language emerge from the following formula (after Hawkins): SOV / POST / GEN + N / N + ADJ. The author, Professor of the Classics and Linguistics at the University of Illinois (Urbana/Champaign), has published fourteen books and over seventy articles on Old Nubian; he is regarded as the World's leading authority on that language.