During what period was the timetable created?
During what period did the agenda initially devised?
In which period did the calendar come
into existence?
In what period was the calendar originally devised?
During what period did the schedule originally thought up?
During what period did the schedule initially devised?
In what period did the calendar creation?
During what period did the timetable come about for the first time?
The Maya Calendar System Smithsonian Institution