In what period did the calendar originated?
During what period was the calendar first introduced?
During what period did the timetable arise?
At what time was the agenda firstly devised?
During what period did the agenda firstly thought up?
During what period was the agenda initially devised?
In which period did the agenda
inception?
In what period did the timetable come about for the first time?
How Did People Count Years Before BC and AD Medium
