In which period was the timetable created?
During what period did the timetable first devised?
During what period was the calendar come into existence?
During what period did the calendar originally invented?
During what period did the timetable initially imagined?
In what period was the timetable firstly devised?
During what period was the agenda generation?
During what
period did the calendar arise for the first time?
Common Era Wikipedia
