Time Frame we live by???

[IrOnLaW]

I have a quick question about the time frame we live by. I am not trying to make any point, but am just curious about this particular subject.

How and when was the time frame we live by created (BC & AD). The entire world goes by this scale, thus I was wondering when it was created. We live by a time frame that is based on the exact day Jesus was born, if I am correct.

What about before Jesus. Did they have a clue of what date it was, or was that just not part of their lives back then? Was it just not in their scope of reasoning of what date it was or how old they were?

So at what point in history was our time frame created? At what point did the entire world decide that, "It is the year ??? AD, and thus I am "so and so" years old."

Modern Civilation has seemed to adopt this particular time frame, so the question is how, when, and by whom was it created?? Also, how and when did it spread across the world of what year it was, and to live by this scale???