Biographical works are usually non-fiction, but fiction can also be used to portray a person's life. One in-depth form of biographical coverage is called legacy writing. Works in diverse media, from literature to film, form the genre known as biography.An authorized biography is written with the permission, cooperation, and at times, participation of a subject or a subject's heirs. An autobiography is written by the person himself or herself, sometimes with the assistance of a collaborator or ghostwriter.One of the earliest of the biographers was Plutarch, and his Parallel Lives, published about 80 A.D., covers prominent figures in theclassical world. In 44 B.C. Cornelius Nepos published a biographical work, his Vitae Imperatorum (“Lives of Commanders”). Perhaps the earliest extant biography that does not contain mythological material is The Lives of the Caesars by Suetonius.In the early Middle Ages (AD 400 to 1450) there was a decline in awareness of the classical culture in Europe. During this time, the only repositories of knowledge and records of the early history in Europe were those of the Roman Catholic Church. Hermits, monks, andpriests used this historic period to write biographies. Their subjects were usually restricted to the church fathers, martyrs, popes, andsaints. Their works were meant to be inspirational to the people and vehicles for conversion to Christianity (see Hagiography). One significant secular example of a biography from this period is the life of Charlemagne by his courtier Einhard.In Medieval Islamic Civilization (c. AD 750 to 1258), similar traditional Muslim biographies of Muhammad and other important figures in the early history of Islam began to be written, beginning the Prophetic biography tradition. Early biographical dictionaries were published as compendia of famous Islamic personalities from the 9th century onwards. They contained more social data for a large segment of the population than other works of that period. The earliest biographical dictionaries initially focused on the lives of the prophets of Islam andtheir companions, with one of these early examples being The Book of The Major Classes by Ibn Sa'd al-Baghdadi. And then began the documentation of the lives of many other historical figures (from rulers to scholars) who lived in the medieval Islamic world.