Anno Domini
The terms anno Domini (AD) and before Christ (BC) are used when designating years in the Gregorian and Julian calendars.
[8] The anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate years in his Easter table.
His system was to replace the Diocletian era that had been used in older Easter tables, as he did not wish to continue the memory of a tyrant who persecuted Christians.
[17] It has also been speculated by Georges Declercq[18] that Dionysius' desire to replace Diocletian years with a calendar based on the incarnation of Christ was intended to prevent people from believing the imminent end of the world.
[19][14] Anno Mundi 6000 (approximately AD 500) was thus equated with the end of the world[18] but this date had already passed in the time of Dionysius.
[21] The historical evidence is too fragmentary to allow a definitive dating,[22] but the date is estimated through two different approaches—one by analyzing references to known historical events mentioned in the Nativity accounts in the Gospels of Luke and Matthew and the second by working backwards from the estimation of the start of the ministry of Jesus.
[23][24] The Anglo-Saxon historian Bede, who was familiar with the work of Dionysius Exiguus, used anno Domini dating in his Ecclesiastical History of the English People, which he completed in AD 731.
[26] On the continent of Europe, anno Domini was introduced as the era of choice of the Carolingian Renaissance by the English cleric and scholar Alcuin in the late eighth century.
Its endorsement by Emperor Charlemagne and his successors popularizing the use of the epoch and spreading it throughout the Carolingian Empire ultimately lies at the core of the system's prevalence.
"Anno ante Christi nativitatem" (in the year before the birth of Christ) is found in 1474 in a work by a German monk.
[29][30][31] When the reckoning from Jesus' incarnation began replacing the previous dating systems in western Europe, various people chose different Christian feast days to begin the year: Christmas, Annunciation, or Easter.
[33] Long unused, this practice was not formally abolished until Novell XCIV of the law code of Leo VI did so in 888.
Byzantine chroniclers like Maximus the Confessor, George Syncellus, and Theophanes dated their years from Annianus' creation of the world.
Eusebius of Caesarea in his Chronicle used an era beginning with the birth of Abraham, dated in 2016 BC (AD 1 = 2017 Anno Abrahami).
Another system was to date from the crucifixion of Jesus, which as early as Hippolytus and Tertullian was believed to have occurred in the consulate of the Gemini (AD 29), which appears in some medieval manuscripts.
The "Common/Current Era" ("CE") terminology is often preferred by those who desire a term that does not explicitly make religious references but still uses the same epoch as the anno Domini notation.
