"BTW, imo, i dont believe the "birthday system" was even use at that time, the culture was too primative to correctly document and verify the authenticity of birth other that the mother, however it was very rare for literate ppl back then. just think, how many ppl in modern times have to look at a calender every once in a while just so they dont miss a doctors appt!"
They had a Calander, you can be sure of that. Yes they were distorted as time progressed because they couldn't calculate those 6 hours(and a little bit) in their system like we have now.
I think it was a pope that discovered that later on. He realized it when December was the first days of the summer time. So a correction was made. And I believe kelts used the lunar cycle.
EDIT: They could also have looked at the seasons. Although this would not work as good while you go deeper in afrika and the middle east.
An idiot could see that the sun is lower during winter and high during summer times. They might not have an exact date but they would have an approximation. They could use the season based time telling. But I think I'm saying the same things over and over again:p. I'm confused myself:p
Not many people know this, but I own the first radio in Springfield. Not much on the air then, just Edison reciting the alphabet over and over. "A" he'd say; then "B." "C" would usually follow...