Even with the chronological information available, as outlined above, it may come as a surprise to realize that it is extremely difficult to fix true or absolute dates in Egyptian chronology. Most of the information given in the inscriptions mentioned is relative, in that it shows a sequence of kings relative to each other with sometimes a length of time between each reign, but to fix them in an absolute framework is a different matter altogether.
Absolute dates from ancient Egypt rely on astronomical dating. This is done by reference to the civil and astronomical calendars in a complicated calculation involving the Sothic cycle of 1460 years, based on the heliacal rising of Sirius, or Sothis, the 'dog star'. The ancient Egyptians knew that the year consisted of 365 days, but they made no adjustment for the additional quarter of a day each year - as we do with Leap Year every four years at the end of February. Hence their civil and astronomical calendars were gradually moving out of synchronization and could bring about extremes of dating between the two. Eventually, every 1460 years, the two calendars coincided and were correct for a short time, until they gradually became out of step again until the end of the next cycle.
|Fixing true dates by the stars|
The occurrence of a heliacal rising of Sirius is recorded in the 7th year of the reign of Senusret III (1878-1841 BC) of the 12th Dynasty. The event is dated to the 16th day of the 4th month of the 2nd season in the 7th year of the king. (There were only three seasons, not four, in ancient Egypt: inundation, sowing and harvest; then the cycle started again.) By calculating from the 'coincidences' of 1317 BC and 2773 BC, this rising can be fixed at 1872 BC.
Another such sighting recorded occurred on the 9th day of the 3rd month of the 3rd season in the 9th year of Amenhotep I (1551-1524 BC); this produces a date somewhere within a 26-year range in the second half of the 16th century BC, since it cannot be quite so closely tied as the Senusret date.
This shows just how fluid Egyptian chronology can be, essentially calculated on a structure of regnal years for each king (where known) and which, by counting backwards and forwards, are basically anchored to the three heliacal risings of Sirius mentioned. It is generally accepted that Egyptian chronology is on a firm footing from 664 BC, the beginning of the 26th Dynasty (Saite Period) and the reign of Psammetichus I. There are then outside links to the chronology of historical Mediterranean civilizations which become firmer as the full classical and Roman periods are reached. Margins of error in the dynasties prior to the 26th are variable; whilst in the New Kingdom 20 years might be acceptable, this will increase as earlier periods are reached so that dates around the unification and in the Early Dynastic Period (Dynasties 0-2) could be subject to fluctuations of anything between 50 and 200 years.
Chronicle of the Pharaohs
Some recent literature, both scholarly as well as ‘fringe’, has suggested outlandish and unacceptable changes in the chronology. Principal amongst the former is Centuries of Darkness by Peter James (1991), and amongst the latter the books of Velikovsky and Von Daniken. It is small wonder then that there is often such a variety in the dates suggested in much of the literature. In this book the dating followed is largely that put forward by Dr William J. Murnane in his Penguin Guide to Ancient Egypt (1983).