And just to be clear, I have also asked similar questions, if coins were not really dated until the 1400s - 1500s time frame how did they keep track of the years from 0 to 1500 ? Who determined what year you were actually in ?When I was in Spain we dug a lot of old coins but the earliest DATED coins were from around 1599 Vatican coins..
The Church I'm sure had something to do with it...
and I'm not really buying the "letter on this ancient coin means X year" because what would have been the first year they started from, because before "CHRIST" there really wasn't a starting year .... or if there was what was it and why did they start all over with Christ ?
When you put a date on something, there HAS to be an assumed starting point, you don't just pull a number out of thin air and say you will start HERE..