What Year is IT?

As we now acknowledge that we are in 2016, 

I wonder if we would be thinking differently if political forces had not decreed the demarcation between before christ and after christ ?

What I mean is suppose we spoke about the calendar in the Jewish, Chinese or Maya sense.  

Suppose we considered this year to  be year 5200, or year 10,000 rather than 2016.

 What do we learn and how  do we learn explicitly or implicitly as a species?