When did the calendar devised?
At what time was the calendar first devised?
In which period was the schedule come into existence?
In which period did the timetable firstly created?
During what period did the schedule originally envisioned?
When was the agenda firstly devised?
In which period did the agenda generation?
At what time did the calendar arise for the first time?
When Was the Calendar Invented A Look at the History and