 Some of these were used for a considerable time.Perhaps the best known is the Era of Martyrs, sometimes also called "Anno Diocletiani" (after Diocletian), which was associated with the Alexandrian calendar and often used by the Alexandrian Christians to number their Easters during the 4th and 5th centuries, and continues to be used by the Coptic and Ethiopian churches.In the eastern Mediterranean, the efforts of Christian chronographers such as Annianus of Alexandria to date the Biblical creation of the world led to the introduction of Anno Mundi eras based on this event.