Spread of the system The B.C./A.D. system gained in popularity in the ninth century after Holy Roman Emperor Charlemagne adopted the system for dating acts of government throughout Europe. By the 15th century, all of Western Europe had adopted the B.C./A.D. system.

When was the dating system created?

525 The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table. His system was to replace the Diocletian era that had been used in an old Easter table, as he did not wish to continue the memory of a tyrant who persecuted Christians.