Right now we mostly use the A.D. and B.C. to tell the passage of years. What did the ancient people (specifically Romans because they were the most powerful civilization near 1 AD) use in, what we consider to be the “B.C.” years or even in the early A.D. years? Obviously you can’t say “I was born in 54 BC” when back then there was no knowledge of Christ.
The Romans dated from the founding of the city (Rome, that is). There’s a latin phrase they used that meant just that, but I don’t remember what it is. According to legend the city was founded in 753 B.C. (though I think scholary opinion is that Rome was actually settled quite a bit earlier), and that’s the date they counted from.
I’m pretty sure this answer has been answered before, but the Romans used A.U.C. (Ab Urbe Condita-From the founding of the city), which dated things from the founding of Rome. More commonly, Romans would use “In the year when X and X were consuls”, there being two consuls of the city, who served for one year. They might also date things by events. To make a comparison, if I wanted to talk about this year, I could say, “In 2001 CE,” or, “In the first year G.W. Bush was president”, or “The year we launched the attack on Afghanistan”