I mean, I never really thought about it, but of course B.C. wouldn't work out considering the guy it was based on hadn't even existed yet.
So, how exactly did they measure years, or did they even bother?
This question gets asked here a lot. Without meaning to stifle further discussion, here are some answers from the FAQ:
In Blackwell's A History of the Ancient Near East, they claim that early Sumerian civilizations went about delineating years by naming them after a significant event that occurred in the previous year. By the 1000s B.C.E, they started naming the years for the king/empires/ruler (i.e. "The fifth year of Sargon of Akkad's reign")