The Bible was written without the use of long distance calendar epochs like we are familiar with today. Two times in Biblical history make good starting epochs. The earliest reasonable starting epoch is Adam’s 1st year. The latter reasonable starting epoch is the Exodus from Egypt. These 2 events are exactly 9500 years apart, 190 Jubilee cycles, making reconciliation between the 2 starting points easy.
Most calendars begin their year counting numbers at some interesting political event. These events are called "epochs". The event had to be important enough in the affairs of the nation to warrant the reset of the ongoing count of years.
The western world has used Jesus’s birth year as the epoch since about the 600s. Before the use of Jesus’ birth year, the Roman world used years counted from the founding of the city of Rome. That city founding provided the previous Western epoch.
Most other nations, indeed, most of the world, throughout most of history, have used the years in the reign of the current king as the Calendar epoch. Even in places where there was an overarching calendar, like years from the founding of the city of Rome, there have been localized uses of king’s reigns for time reporting.
The value of the king’s reign as the epoch was that the year counts used by the average citizen were low. Most kings throughout most of history have reigned for under 30 years. Thus the year number would reset to 1 each time a new king came to power and the entire date would not have a number over 30. This pattern is also seen in Luke.
1In the 15th year of the reign of Tiberius Caesar, during the governorship of Pontius Pilate in Judah, when Herod was tetrarch of Galilee, and his brother Philip, tetrarch of Iturea and of the region of Traconitis, and Lysanius, tetrarch of Abilene,
2during the high priesthood of Annas and Caiaphas, the word of god came to John, son of Zechariah, in the wilderness.
Here Luke records that John the Baptist was called by God to his ministry in the 15th year of the reign of Tiberius Caesar. In the Bible the use of the king’s reign, or patriarch’s life, is seen fairly clearly. Most references are given relative to a king’s reign or to a patriarch’s life.
The modern world, with proper year counts in the hundreds, has adopted a different strategy for keeping the year number low for most citizens. The strategy has been to use only the last two digits of the actual year. Thus, 1999 becomes 99 and everyone just knows this refers to the closest actual year who’s last two digits are 99. This is not much different than the year in the king’s reign since it still keeps the numbers low.
Bigger epochs, though, are interesting because most modern people have the ability to comprehend numbers in the thousands. This is important since we can understand the flow of history to large numbers, so rather than leave the biblical calendar as a large set of disjoint time segments we want to think of the Biblical calendar in a way similar to our modern calendar. We want large numbers counted from some starting Epoch.
The 2 natural Bible epochs are Adam’s 1st year, being the 1st year of Adam’s race, and the Exodus, the 1st year the Israelites were out of Egypt.
Both of these systems of natural epochs are used for presenting dates by the Bible Time online tools.
Note that these 2 natural Epochs are exactly 9500 years apart, an even number of Jubilee cycles. This means that the year within the Jubilee cycle, the month as well as the day are the same using either of these Epochs.
In order to mark the 2 Epochs, dates are reported here using a calendar mark at the end of the date. Consider, the date that the Israelites came out of Egypt, was the following:
9501/1/15 AA 1/1/15 FE
The AA stands for "After Adam."
The FE stands for "From Exodus."
Understand that these are simply different labels for the same day.
Most modern dates are written without any epoch notation. A date like March 2, 2010, is assumed by the writer to be on our standard modern Gregorian date system. There are, though, 2 different notations that exist as a convention for modern dates.
NS is the implied marker for modern or "New Style" dates. This marker has been used worldwide as countries have adopted our New Style system of Gregorian dates.
OS is the worldwide conventional notation for the "Old Style" Julian date system that supplanted the modern Gregorian system.
To be rigorous, the date mentioned earlier would be written as March 2, 2010 NS.
Note that the Russian world remained on the OS, or Julian calendar until the communist revolution. Except that in the year 1700 they had moved New Years day from March 25, to January 1. English language Russian history textbooks are usually rigorous in this regard, and all dates are usually given with either an NS or OS notion so that the reader does not accidentally re-convert the date from one calendar to the other. Accidental over conversion is called drift error.
The Bible Time date tools use the OS and NS conventions to warn readers which calendar system is implied. The OS system,and mark, follows the OS calendar used by Rome, with a new years day on March 25 of each year. It is predictable and follows known conventions back to the year 5 AD. Before 5 AD there are a considerable number of assumptions and there are various ways to interpret the calendar for OS style dates.
Note also that most western countries at some point in their history had their own calendar intentionally out of sync with the calendar kept at Rome. For complete historical analysis there are times when the local national calendar must be consulted.
Jesus’ life has been used as an epoch for the secular western calendar for around 1400 years. Why would we choose not to use that system here?
Jesus’ birth is not exactly on the Jubilee cycle used to measure time through the rest of the Bible. His age 12 visit to Jerusalem was the millennium celebration in his life, which was the Jubilee.
Using this epoch creates considerable numbers of negative dates which cause confusion.
The modern calendar is built with this epoch, yet the modern calendar uses a slightly different year length. Use of this epoch, but with the Bible’s calendar would cause dates off by a little which would be still more confusing. There is already the problem of date drift caused by the different year lengths used in the western world.
The Bible Time project is now it its 10th year. In recent work the project has started minimizing the use of the "FE" or Exodus Epoch dates.
Initially the FE system allowed debate on dates measured from the Exodus, without the tension of the long rendering of Genesis 5 and 11 contributing to the debate. The FE Epoch date system also allows for dates with only 4 digit years which initially felt more natural.
But, it often takes space to state dates using 2 different notations and it leads to the problem of negative year numbers for events before the Exodus. Negative years don’t happen for dates since Adam using the AA system. (Of course negative dates still do occur for creation week dates but there are no known dated events in this era.)
As you read through Bible Time articles, note the AA and FE notations are there to precisely indicate the system used to label the date.