A.M. – Anno Mundi. This calendar was used by several of the Byzantine authors including Theophanes and Anastasius Bibliothecarius.
The calendar is based on the Julian calendar however the year does not begin on 1 January and the starting day, month, and year of
this calendar was a point of contention as it was based on an estimate for the start of "creation"
(among other things)
as interpreted through the Septuagint - a Greek translation of the Old Testament. An ongoing several hundred year long
theological debate over when Biblical "creation" began led to multiple versions of the A.M. calendar. The earlier Byzantine
sources used the Alexandrian version (A.M.a) or “Alexandrian era” of this calendar which has a starting date of 25 March 5492 BCE or,
according to Bickerman (1980), 25 March 5493 BCE. Earthquake catalogers Guidoboni et al (1994) and Ambraseys (2009) assume a starting date of
25 March 5492 BCE and that is what I use. As explained by Grumel (1958:219)
The Alexandrian era of Panodorus began in 5493 BCE [and] the Alexandrian era of Annianos began in 5492 BCE. The Alexandrian Era of Annianos
is what is commonly called the Alexandrian era.
Another reckoning system, used for example by Megas Chronographos, is the Byzantine version (A.M.
Byz) which has a starting date of
1 September 5509 BCE (Bickerman, 1980:73-74). Yet another reckoning system is a variant suggested in Chronicon Paschale which was composed in ~630 CE. The starting
date for this system is 21 March, 5507 BCE. In the Anno Mundi calendar system used by the Byzantine authors, the day followed the Roman civil
custom of beginning the calendarical day at midnight. When hours are indicated they mark time since dawn. Hence, if daybreak began at 6 am,
the 4th hour would correspond to 10 am (Rautman, 2007:3).
Calendaric Inconsistencies of Individual Authors
Author |
Inconsistencies |
Theophanes |
Grumel (1934:407), Proudfoot (1974:373-374), and others have pointed out that Theophanes A.M.a
in the years A.M.a 6102-6206 and A.M.a 6218-6265 are frequently a year too low. |