We have marked the alleged 2013th year since Jesus's birth coming up on January 1. This, of course, is not unrelated to December 25th being the birthday of Jesus, whose life was the impetus behind the "Christian" religious movement, which enjoyed widespread popularity over the past 2000 or so years.
While many modern commentators insist that Jesus' birthday actually represents the tailoring by the 4th Century Emperor Constantine of the celebration of the sun god in a Roman religion popular among soldiers, there are second or third century references to Jesus's birth being celebrated on the 25th of at least two Egyptian calendar months.
Apart from the month and day, the year presents its own set of problems. It appears that Dionysius Exxugus (Dennis the great?), a fifth (?) century monk, was given the task of revising the calendar, and was allegedly the first to count the years from the birth of Christ. The question, as I see it, is, what criteria did he actually use to choose the year of Jesus's birth.
I think there is a possibility that he used a calendrical cycle that began close to the approximate time indicated in the bible. It is of little utility to contemplate the actual year of Jesus's birth, but it is of immense interest to attempt to understand how Dennis the great managed to arrive at his date, since our current calendar is dependent upon it.