Byzantine calendar
The Byzantine calendar was a calendar used by the Eastern Orthodox Church from the year 691 A.D. to 1728. It was also used by the Byzantine empire from 988 A.D. to 1453, when the empire fell, and by Russia from 988 A.D. to 1700. The Byzantine calendar is like the Julian calendar, but the year starts on 1 September instead of 1 January. Year one of the Byzantine calendar is from 1 September, 5509 B.C. to 31 August, 5508 B.C.