We get questions like this a lot! I should keep track of answers by other people, since I know I've seen posts about Islamic and Hebrew calendars, and various ancient Roman and Persian ways of counting years...but for now, apparently I've written a lot about this too, and I have a list of a few of my own previous answers at least:
Greek calendars using the Olympic games as a reference point.
By the Romans reckoning, what year was Caesar assassinated?
Did the Eastern Roman Empire date by Anno Domini or by Ab Urbe Condita?