As soon as Anderson's Constitutions were published in 1723, the reference to a date 4000 years older than that of the current calendar appears on the title page!
In the text of the Constitutions there is no demonstration of this, but we can think that James Anderson's source is to be found in the English translation of the Bible, well known under the acronym KJV for "King James Version", whose publication in 1611, during the reign of King James VI of England and Scotland, was a real literary and religious event because it was the first time that the people of England could access the Bible through its language.
In the notes of the KJV Bible, reference is made to the dating of Archbishop Ussher, Irish Anglican Archbishop and Primate of Scotland, which sets the beginning of the world at 4004 B.C. (The 4 year difference is related to the supposed date of birth of Jesus Christ).
Still, in 1723, James Anderson uses the date 5723!
Although we are already under the era of the Gregorian calendar, by fidelity to the Julian calendar, the beginning of the Masonic year will remain fixed at March 1st!
As it is always easier to "make complicated" than to remain simple, other Masonic calendars will appear with more or less folkloric dates!
The Masonic year exposes the secretaries of the lodges to a muddle for the period of the first two months of the year because, for example in February 2018 we were still in 6017, and for the count of the months, because we do not say "April 6018" but the 2nd month of the year 6018; we sometimes add AVL (for Year of True Light) or AL (for Anno Luci).
The reflection on the calendars of the different cultures is interesting because it allows us to realize how much the legendary creations of the past are still alive today!