There was, of course, no year 0, and for several reasons. One is that the zero had not yet been invented: that happened in India, probably in the seventh century AD. Another is that many people around the world, then as now, were not Christians, and conceived time in completely different ways. A third reason is that the conventional chronology, used for dating events in the West over several centuries–AD, for Anno Domini, the year of Our Lord, and BC, before Christ–was not introduced until the sixth century.
