What year is it? From Archons to Anno Domini: Early Western Dating Systems
Around 500 BC the Greeks began dating events by reference to the name of an important local office holder e.g. the priestess of Hera at Argos or the archon at Athens. Herodotus, for example, wrote that Xerxes reached Athens during the archonship of Calliades.
The system continued alongside a slightly later one based on the four-year cycle of Olympiads which became popular because – being national – it needed no local knowledge. However, few could initially agree on when the “first” Olympiad was and so several models (based on semi-mythical firsts or historical winners) vied for supremacy. In the end, an Olympics dominated by Coroebus of Elis (who won the main event, the stadion) became the most popular starting-year. Following its widespread adoption around the second century BC it flourished for another eight centuries.
The first author to create a system capable of displacing the Olympiads was Eusebius (d. 339), who dated events by reference to the regnal years of kings and by years from the birth of Abraham (which had been calculated from information in the Septuagint). According to his jottings Abraham had been born 3184 years after the creation of the world, so “years from Abraham” could be converted into “years of the world” i.e. Anno Mundi (AM) simply by adding 3184. Isidore of Seville pulled off a similar manoeuvre but assumed a slightly younger world. Bede also devised a world-era system in England. In his Reckoning of Time, completed in the ninth year of the emperor Leo III, the historian also abridged the timescale to Adam (compared to the Septuagint used by Eusebius).
Some of the simplest systems gained the most traction. Dating events according to the regnal years of rulers, for instance, was always popular and few figures loomed larger in this sphere than Diocletian (perhaps because he was the first to bring peace and stability after constant civil war). In Egypt, events continued to be dated from his first regnal year even after the end of his reign. Indeed, even though though Diocletian had persecuted Christians the Alexandrians used this system to date the years in their Easter Tables (which gave the future dates for Easter Sunday determined on the basis of a 19-year lunar cycle). The Diocletian “Era” system – subsequently renamed the “Era of Martyrs” by disgruntled Christians – is still in use by the Coptic Church today. During the Byzantine period histories such as the chronicle of Theophanes the Confessor began with the first year of Diocletian (making Anastasius assume the purple in the 207th year of Diocletian).
Regnal rules were really a continuation of the traditional Roman system that pinned dates to the reigns of their consuls. After the expulsion of the last king Tarquinius Superbus, his nephew Junius Brutus and Tarquinius Collatinus (a nephew of Tarquin the Elder) were appointed the republic’s first consuls. Annual consuls continued to be appointed long after the “empire” was established, indeed the practice effectively lasted until the reign of Justinian when the office was absorbed by the emperor.
Another Roman dating system was ab urbe condita. Which sounds a lot more technical and accurate than it really was considering nobody was very sure when Rome had been founded. Authorities varied between 38 years before the first Olympiad (Limaeus of Sicily) and the sixth (Varro). The latter’s dating became the official one but, even then, the system was only ever used to mark important anniversaries. Indeed, among the few historians to take it up in earnest were (the fairly late figures of) Eutropius and Orosius.
Beneath the grand systems burbled more regional accounts of time. Spain – for no apparent reason – appears to have chosen 38 BC as the “start” of their “Spanish Era.” Hydatius, John of Biclaro and Isidore of Seville all used it. Rather eccentrically this Spanish reckoning continued for several more centuries with even twelfth-century chronicles adopting the system. Elsewhere the Antiochene Era began when Caesar defeated Pompey. John Malalas, for instance, wrote that Marcian reigned from 499 in the Antiochene Era. Furthermore, the Seleucid Era (sometimes known as the Greek or Alexandrian Era) also originated in the region. Its trigger was the victory of Seleucus over Demetrius (312 BC) which led to the institution of the Seleucid dynasty.
In the East, the Romans preferred systems that dated the world’s origin by linking interpretations of passages in scripture to astronomical cycles (the Chronicon Paschale is a good example). Subsequent chronicles written in Constantinople tended to use AM 6321 which became the official dating system of the Eastern Roman (Byzantine) Empire. The capture of Constantinople by the Ottomans was therefore dated to AM 6961 by the Byzantines and AD 1453 by the Venetians. Fascinatingly, the Byzantine Era system remained the official Russian one until the reforms of Peter the Great whose calendar changed from AM 7208 to AD 1700 on the 1st January. Although no longer in general use by the Eastern Orthodox Church it still forms the basis of the traditional Orthodox calendar. The year AD 2000 corresponded to AM 7508/7509.
Back in the West, although the tables of Victorius were initially used it became apparent that their understanding of the Alexandrian methodology was flawed. This rarely affected the outcome but it nevertheless created an uncomfortable situation in Rome which was meant to be an authority on such matters. So when the 95-year set of tables (comprising five 19-year lunar cycles) commissioned by Cyril, patriarch of Alexandria, approached its expiration date the pope called on Dionysius Exiguus – a Scythian monk living in Rome – to produce a continuation. Dionysius labelled each annual entry with an Anno Domini (AD) date that related to the birth of Jesus Christ (rather than continue the Diocletian Era used by Cyril).
The first historian to use the AD system for historical events was Bede. He wrote that Marcian, for example, became emperor in AD 449 but he could not have found that date in any of his sources because he was starting a new tradition by using the AD system. Across Europe others quickly imitated him. Indeed, Frankish chronicles from Bede onwards used AD dates. The system’s only real competition came from the “Victorian” dates of Victorius of Aquitaine who used a popular method known as the Anno Passione (AP) system i.e. years from the crucifixion and resurrection of Christ. Tasked by Hilarus (later a pope) with producing a set of Easter Tables to remove the West’s dependence on tables produced in Alexandria, he provided a 532-year cycle of dates starting in AP1 and ending in the 18th year after the consulship of Basilius (the reign of Justinian).