Did BC or AD come

BC (Before Christ) refers to the years before the traditional date of the birth of Jesus Christ, while AD (Anno Domini, Latin for "in the year of our Lord") refers to the years following that event. Therefore, BC came before AD. The transition marks a significant point in the Christian calendar, with AD starting at year 1. There is no year 0 in this system; the year immediately before AD 1 is 1 BC.