Jews in these regions used Seleucid Era dating (also known as the "Anno Graecorum (AG)" or the "Era of Contracts") as the primary method for calculating the calendar year. Jacob then put this question: How do we know that our Era [of Documents] is connected with the Kingdom of Greece at all?
Why not say that it is reckoned from the Exodus from Egypt, omitting the first thousand years and giving the years of the next thousand? Said Rav Nahman: In the Diaspora the Greek Era alone is used.
Patriarchs from Adam to Terah, the father of Abraham, are said to be older by as much as 100 years or more when they begat their named son in the Greek Septuagint than they were in the Latin Vulgate (Genesis 5; Genesis 11) or the Hebrew Tanakh (Gen 5; Gen 11).
If you think dating is complicated now, wait until you see how frigging confusing dating in the Victorian era was.
Sure, there were all the constricting social rules and mores that dictated how one was supposed to behave.
Anno Lucis (“in the Year of Light”) is a dating system used in Masonic ceremonial or commemorative proceedings, which is equivalent to the Gregorian year plus 4000. in accordance with the Seder Olam Rabbah compiled by Jose ben Halafta in 160 AD, and in agreement with The Remaining Signs of Past Centuries, in which the Muslim chronologist al-Biruni identifies anno mundi as 3448 years before the Seleucid era but not with Seder Olam Zutta, which dates it to 4339 BC and was compiled in 804 AD.
Among the Masoretic creation estimates or calculations for the date of creation, Archbishop Ussher's specific chronology dating the creation to 4004 BC became the most accepted and popular in Christendom, mainly because this specific date was attached to the King James Bible.