Ancient dating systems
By the 15th century, all of Western Europe had adopted the B.
D.) year numbering, sometimes secularized as "BCE" (Before Common Era) or "CE" (Common Era). D." stands for , Latin for “in the year of the lord,” and refers specifically to the birth of Jesus Christ. C." stands for "before Christ." In English, it is common for "A. In the early Middle Ages, the most important calculation, and thus one of the main motivations for the European study of mathematics, was the problem of when to celebrate Easter. Computus (Latin for computation) was the procedure for calculating this most important date, and the computations were set forth in documents known as Easter tables. Dionysius devised his system to replace the Diocletian system, named after the 51st emperor of Rome, who ruled from A. (Let's not even discuss Year Zero, seeing as this jockeying for Year One position occurred before the concept of zero had even been invented.) If we wanted to allow for commerce, trade, and simple communication across cultures to develop, we needed to be living in the same year. The Byzantine Empire started its first year in what was considered the year of creation (our 5509 B. The Church of Alexandria began its Year One in what is now 284 A. And two, when most people see it, they think it stands for Christian Era and Before Christian Era, so it doesn't really solve the problem people wanted to solve.” As the world continued to “shrink” due to the establishment of trade routes and expansion of population and as once-insular communities started opening up and exploring, a single Year One would have inevitably dominated.The Greeks were among the first to try to get everyone running on the same year. D., to coincide with the rise of Roman emperor Diocletian into power. C.—that is, “before Christ”—wasn't introduced until 1627, by a French astronomer. D., so decided to figure that in by counting backwards. The specifics of which one are not particularly important.