The Anno Domini dating system was devised in 525 by
Dionysius Exiguus
exiguus (feminine exigua, neuter exiguum); first/second-declension adjective. strict, exact. paltry, inadequate.
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When was the first year ever?
AD 1 (I), 1 AD or 1 CE is the epoch year for the Anno Domini calendar era. It was the first year of the Common Era (CE), of the 1st millennium and of the 1st century.
Who started year 1?
A monk called Dionysius Exiguus (early sixth century A.D.) invented the dating system most widely used in the Western world. For Dionysius, the birth of Christ represented Year One. He believed that this occurred 753 years after the foundation of Rome.
