Dating custom in italy
In the empire it only became general in the latter part of the ninth century, while although it occurs occasionally in papal documents of the time of John XIII (965-972), it was not the rule before the twelfth century.
So far as regards the emperors this was prescribed by Justinian (Novella xlvii).
On the other hand, the last three agree in using the Christian Era and from this time the practice is continuous.
In the intervening year which breaks this series into two parts falls the death of Bede A. 735." Very noteworthy is the decree of an English synod held in 816, wherein it is prescribed that the bishop shall put the acts of the synod into writing and date them by the Era of the Incarnation.
Although, as explained in the article GENERAL CHRONOLOGY, the monk known as Dionysius Exiguus, when resident in Rome, c.
527, seems to have been the first to initiate the practice of calculating years from the birth of Christ and although it was undoubtedly he who identified the year of Christ's birth with the year 753 of the foundation of Rome, as is still done in our current chronology, nevertheless it was not until long after the age of Dionysius Exiguus that the system came into common use.
It was the pope's habit to date his letters by the regnal years of the emperor and letters so dated may be seen in Bede's "Ecclesiastical History", just as they were copied from the Roman archives.