There are approx. 40 diff. calendars used world-wide mainly for determining religious dates. Most modern countries use the Gregorian calendar. 3 basic types of calendar: Lunar, Solar & Lunisolar Historically calendars have varied in many ways: 1. Diff start dates 2. Varying lengths of years as well as Leap years with huge variations 3. Differing number of months and lengths of months 4. Varying numbers of days in the week (5-13 days), and odd methods of counting We will primarily just give a brief overview of the Roman, Julian, Gregorian and Hebrew calendars. The calendar years will be denoted as follows: 1. Roman (AUC) 2. Julian (AUC) 3. Gregorian (BC & AD) 4. Hebrew (AM) A. AUC 1 / 734 BC Roman Calendar The Roman calendar was dated from the foundation of the city of Rome. (supposedly by Romulus) Borrowed from the idea from the Greeks but only initially only used 10 months (304 days/year) They had 3 beginning dates: 1 May/15 March /1st Jan B. About AUC 50 / 700BC Because their years were short by about 60 days, the calendar wasn’t lining up with the seasons. King Numa Pompillius added the months January & February (354 or 355 days – still 10 days short) The days weren’t counted numerically for the month but in relation to phases of the moon ref’d. as Kalends/Nones and Ides C /D. AUC 688 / 46 BC Julian Calendar By this time the calendar required some major adjustments. Julius Caeasar rolled the existing Roman lunar calendar (Inaccurate) over into the Egyptian (solar) calendar with some major adjustments. To realign - added 3 months into 46 BC (1 extra month after February & 2 extra months after November) which became almost identical to the current Gregorian calendar. E. It seems that it was customary during the Renaissance for editors to add “AUC” to Roman documents giving a false impression of a convention of dating. Generally the dominant method in Roman times of identifying years, was to name the two consuls that year, without reference to the year itself. F/G AUC 1281 / 527 AD Gregorian Calendar Dionysius Exiguus - introduced system of numbering AD 1 AD was calculated as AUC 754 (the incarnation) H The rule for leap years was changed with some adjustments, (10 days deleted for correction). i.e. 5/10/1582 - 14/10/1582 never existed, (Thur 4th Oct was followed by Fri 15th Oct). I A.M. Hebrew calendar 12th Century Maimonaides calculated creation date from Jewish records. Length of years can be: Common yr: 12 months, 353-355 days Leap yr: 13 months, 383-385 days J Discrepancy between Rabbinic dates and secular dates during the Medo, Persian era. (AM3390-3442 / 370-316BC). Destruction of the Temple Secular / 587 BC Rabbinic AM 3338 / 422 BC Discrepancy 165 yrs but by Alexanders Conquests Secular 312 BC Rabbinic 334 BC Discrepancy 22yrs K Even modern history is not that easy to correlate, as it’s not just a case of lining up two functional timelines. Invariably they are a very different, sometimes somewhat dysfunctional and change over time. Despite the perception as with the Roman situation, historical records often related to the time frame within the reign of a king, punctuated it with references to any major event (like an Olympiad) or natural events (solar eclipses) and disasters (earthquakes & wars). Even with the Jewish records 1996 Israel celebrated Jerusalem 3000 yrs (based on secular date of AM 2757 / 1004 BC for King Davids conquest of Jerusalem). For Torah observant Jews it was only 2,865 yrs (135 yrs diff.) AM 2892 / 869 BC .