What year when BC and AD introduced? There are many different systems for dating. Muslims begin their calendar from the Hegira, the flight of Muhammad from Mecca in AD 622. The Christian calendar, now widely used worldwide, begins with the birth of Jesus. Dates before then are followed by the letters ‘BC’ (Before Christ). Dates after then are prefixed by the letters AD (Latin Anno Domini, or Year of our Lord). AD dating was suggested by a monk-mathematician named Dionysius Exiguus in the year 525. It was much later that BC was used, in the 16oos.
