Systems in use included consular dating, imperial regnal year dating, and Creation dating.
Although the last non-imperial consul, Basilius, was appointed in 541 by Emperor Justinian I, later emperors through Constans II (641–668) were appointed consuls on the first of January after their accession.
At the time, it was believed by some that the resurrection of the dead and end of the world would occur 500 years after the birth of Jesus.
The old Anno Mundi calendar theoretically commenced with the creation of the world based on information in the Old Testament.
This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus of Nazareth, with AD counting years from the start of this epoch, and BC denoting years before the start of the era.Two major theories are that Dionysius based his calculation on the Gospel of Luke, which states that Jesus was "about thirty years old" shortly after "the fifteenth year of the reign of Tiberius Caesar", and hence subtracted thirty years from that date, or that Dionysius counted back 532 years from the first year of his new table.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.The last year of the old table, Diocletian 247, was immediately followed by the first year of his table, AD 532.
When he devised his table, Julian calendar years were identified by naming the consuls who held office that year—he himself stated that the "present year" was "the consulship of Probus Junior", which was 525 years "since the incarnation of our Lord Jesus Christ".
Bede used the expression "anno igitur ante incarnationem Dominicam" (so in the year before the incarnation of the Lord) twice.