How do you work out BCE dates from tablets containing the day of the month and month?

Question

Tablets etc have been found containing the year of someone's reign eg twelfth year, the date eg 5th and the month of that year. We have then changed this somehow into a date relating to the modern calendar. How was this possible?

Answer 1

The reign of "ancient" kingdoms affected near by countries...for instance....when Assyrian/Babylonian kings listed their conquests, the conquered nation's accounting would verify their capture....
Certain keynote dates could be ascertained by comparing Egyptian writings of wars with Assyrian/Babylonian/Hittite/Hurrian records. The Egyptian historical record as preserved in their hieroglyphics was and is a major point of reference...
After Alexander conquered the area, especially after Roman times...there was a wealth of independent, attainable history to determine...more or less...an approximate time line for western bce events...

Add archaeological artifacts, carbon dating, literary references...
it is possible to get a fairly close approximation.

Answer 2

I assume you're talking here about Mesopotamian chronology.

Most "absolute" chronologies of the ancient world are floating chronologies to some extent. What this means is that they are accurate to within a few decades or a few hundred years, but in many cases specifics are up to debate among scholars. Thus in Mesopotamia you have the High, Middle and Low Chronologies with different scholars suggesting different absolute dates.
These chronologies are based on a number of lines of evidence. - ie. king A ruled before king B and king A ruled for 15 years, mentions of certain events that we can fix in time with an absolute dates, such as some astronomical events and some natural disasters. They are also tied closely to events in neighboring regions, such as Egypt. Egyptian chronology does have it's own occasional problems, but it is better understood than most periods in Mesopotamia.
So, working from information such as the order of kings, the lengths of their reigns, and certain significant events that may have occurred during their reigns, we can establish a chronology. Using independently dated events, such as eclipses or other astronomical events, we can then establish the date for that event using our own calendar and work backward and foreward from that date to build chronologies for the ancient past.

Answer 3

that was real confusing to me at first.
They hinge everything on the year that Jesus was born.
then they count backwards. from Jesus to adam with jesus as one and Adam as 4026 BCE Before the Christian era.

then for our time they go forward from Jesus 1 to 2006

Man's been here for 6032 years. They know the date of Jesus.
By the kings ruling mentioned and he was the son of and how long he lived. Some characters are mentioned in secular history.
cordinateing all that. They know how long we been here.
Scholars took years to fingure it all out. That way they say we can have everything in the right time frame.