1st millennium

The 1st millennium was the first period of 1,000 years that started on January 1, 753 AUC and ended on December 31, 999 AD. During the first 541 years, the Julian calendar was using the Ab Urbe Condita system to number years, until the year 525 where the Anno Domini year numbering system was created by Dionysius Exiguus, but was not used until the year 542.