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TheCanon of Kings was a dated list of kings used by ancientastronomers as a convenient means to date astronomical phenomena, such aseclipses. For a period, the Canon was preserved by the astronomerClaudius Ptolemy, and is thus known sometimes asPtolemy's Canon. It is one of the most important bases for modern knowledge ofancient chronology.
The Canon derives originally fromBabylonian sources. Thus, itlists Kings of Babylon from 747 BC until the conquest of Babylon byAchaemenid Persians in 539 BC, and thenPersian kings from 538 to 332 BC. At this point, the Canon was continued by Greek astronomers inAlexandria, and lists theMacedonian kings from 331 to 305 BC, thePtolemies from 304 BC to 30 BC, and theRoman andByzantine Emperors, although they are not kings; in some manuscripts the list is continued down to theFall of Constantinople in 1453.[1]
The Canon only increments by whole years, specifically theancient Egyptian year of 365 days.[citation needed] This has two consequences. The first is that the dates for when monarchs began and ended their reigns are simplified to the beginning and the ending of the ancient Egyptian year, which moves one day every four years against theJulian calendar.[2] The second is that this list of monarchs is simplified. Monarchs who reigned for less than one year are not listed, and only one monarch is listed in any year with multiple monarchs. Usually, the overlapping year is assigned to the monarch who died in that year, but not always. The two periods in the Babylonian section where no king is listed the first represents two pretenders whose legitimacy the compiler did not recognize, and the second extends from the year Babylon was sacked bySennacherib, King ofAssyria to the restoration ofEsarhaddon.[2][3]
The Canon is generally considered by historians to be accurate, and forms part of the backbone of the commonly accepted chronology from 747 BC forward that all other datings are synchronized to.[1] It is not, however, theultimate source for this chronology; most of the names and lengths of reigns can be independently verified from archaeological material (coinage, annals, inscriptions in stone etc.) and extant works of history from the historical ages concerned.