The best I gather is they got it from Sumer about the time when their civilization was splitting apart. Thoth, designer of the pyramids and the calendar, is often credited with this.Posted by IndigoStar (here)
Well where did the Mayans get their info from? They are able to predict every lunar eclipse up to date within 30 seconds, from when they made the calendars all those years ago. So how did they know where to start the calendar?
One thing's for sure. Like the Egyptians, they didn't just up and figure this s**t out one day. LOL
Cheers,
Fred