The title probably isn't very clear, but i couldn't really think another way to put it, but i was just reading the Thales of Miletus article on the Wikipedia when i read he predicted a eclipse on 585 BC.
I started to wonder, how would he tell which years would it happen? did they have another starting point for years instead of our BC and AC?
Not sure i'm being clear here, don't know how to put in words my question. Also, sorry for my english, not my first language.
I think ancient timekeeping is pretty interesting. Here is one thread which discusses it. You might find other interesting threads in the FAQ .
I'll quote /u/Algernon_Asimov who had a nice succinct answer:
Before the AD/BC calendar came along, there were many methods used by cultures to keep track of years.
- The most common way was to record things as happening "In the eighth year of the reign of King/Chief Mogwai": the regnal year[2] system.