News from the chronology of the Nativity came up in the 8th century Bashny.Net

Chronology of the Nativity, and with it the concept of "common era" appeared about fifteen hundred years ago, when Pope John I commissioned the scholar monk Dionysius Small Scythian origin make up the table to calculate the date of Easter. In the early Middle Ages in Europe a few years from the beginning of the reign of the Roman Emperor Diocletian (284 years BC. E.). Instead of the date of accession of the pagan persecutor of Christians and Dionysius the Little took as its starting point the expected date of birth of Jesus Christ. Its he calculated, guided by the text of the New Testament. Today it is considered that the monk made a mistake four years, and our 2011 should be 2007.

Dionysius performed this work in the year 525. In the VIII century, a new dating was extended thanks to the Anglo-Saxon chronicler Bede, who relied on the system of Dionysius in his book "On the six ages of the world." From the same date Bede went to custom events that occurred before Christ ("BC"), scoring in the opposite direction. Gradually, the whole of Europe began to measure time from the birth of Christ. Russia has moved to a new account "for the sake of a better agreement with the European peoples in the contracts and treatises" in 1699 by decree of Peter I.

via factroom.ru