I thought the New Millennium already started
January 1, 2000 is not the beginning of the new millennium. The world has many systems of calendars. The one that brings us the year 2000 was created by a monk named Dionysius Exiguus (literally translated Dennis the Short) in the sixth century. After much study, he determined that time should be marked by the birth of Jesus. He set that time in the year we know as 1 AD. In this calendar, time counted backwards from the year 1 AD to the year 1 BC - with no year 0 in between. By setting the start date as he did, Dionysius also started the First Millennium at the beginning of year 1 AD. So the Second Millennium began at the start of year 1001 AD, and the upcoming Third Millennium will start at the beginning of year 2001 AD.