Each olympiad started with the holding of the games, which originally began on the first or second
full moon after the
summer solstice. After the introduction of the
Metonic cycle about 432 BC, the start of the games was determined slightly differently. Within each olympiad, time was reckoned by referring to its 1st, 2nd, 3rd, or 4th year. Ancient writers sometimes describe their Olympiads as lasting five years but do so by
counting inclusively; in fact each comprised a four year period. For example, the first year of Olympiad 140 began in the summer of 220BC and lasted until the middle of 219BC. After the 2nd, 3rd, and 4th years of Olympiad 140, the games in the summer of 216BC would begin the first year of Olympiad 141.
Historians The
sophist Hippias was the first writer to compile a comprehensive list of the Olympic victors (,
olympioníkes). Although his
Olympic Record (,
Olympionikō̂n Anagraphḗ) is now entirely lost, it apparently formed the basis of all later Olympic dating. The numbering of Olympiads was introduced by
Eratosthenes or
Timaeus; the first on the list occurred in 776 BC. The panhellenic nature of the games, their regular schedule, and the improved
victor list allowed Greek historians from Eratosthenes onwards to use the Olympiads as a way of reckoning time that did not depend on the various calendars of the
city-states. The first to do so consistently was
Timaeus of
Tauromenium in the third centuryBC. Nevertheless, since for events of the early history of the games the reckoning was used in retrospect, some of the dates given by later historian for events before the 5th centuryBC are very unreliable. Because the Olympics occurred in mid-summer, the years reckoned by the Olympiad system aligned with the
Attic calendar (which names years by the names of
archons, not numbers) of
Ancient Athens, but not with
Roman consular years (which began on 1 January) or
Ancient Macedonian calendar years (which began in the autumn). In the
2nd century,
Phlegon of Tralles summarized the events of each Olympiad in a book called
Olympiads; fragments survive in the work of the
Byzantine writer
Photius. Christian chroniclers continued to use this Greek system of dating as a way of synchronizing
biblical events with Greek and Roman history. In the
3rd century,
Sextus Julius Africanus compiled a list of Olympic victors up to 217BC, and this list has been preserved in the
Chronicle of
Eusebius.
Examples of Ancient Olympiad dates • Early historians sometimes used the names of Olympic victors as a method of dating events to a specific year. For instance,
Thucydides says in his account of the year 428 BC: "It was the Olympiad in which the
Rhodian Dorieus gained his second victory." •
Dionysius of Halicarnassus dates the
foundation of Rome to the first year of the seventh Olympiad, 752 & 751BC. Since Rome was founded on 21 April, which was in the last half of the ancient Olympic year, it would be 751BC specifically. In Book 1 chapter 75 Dionysius states: "...Romulus, the first ruler of the city, began his reign in the first year of the seventh Olympiad, when
Charops at Athens was in the first year of his ten-year term as archon." •
Diodorus Siculus dates the Persian invasion of Greece to 480BC: "Calliades was archon in Athens, and the Romans made
Spurius Cassius and
Proculus Verginius Tricostus consuls, and the Eleians celebrated the Seventy-fifth Olympiad, that in which
Astylus of Syracuse won the
stadion. It was in this year that king Xerxes made his campaign against Greece." •
Jerome, in his
Latin translation of the Chronicle of
Eusebius, dates the birth of
Jesus Christ to year 3 of Olympiad 194, the 42nd year of the reign of the emperor
Augustus, which equates to the year 2BC.
Anolympiad Though the games were held without interruption, on more than one occasion they were held by others than the
Eleians. The Eleians declared such games
Anolympiads (non-Olympics), but it is assumed the winners were nevertheless recorded.
End of the era During the
3rd century, records of the games are so scanty that historians are not certain whether after 261 they were still held every four years. Some winners were recorded though, until the 293rd Olympiad of AD393. Although the end of the games has sometimes been linked to the
anti-pagan laws of
Theodosius I (391–392) or
Theodosius II (435), this is no longer widely accepted. The last games at Olympia were probably held in the first half of the 5th century. The last datable
Olympic festival took place at
Antioch in 520. Dating by Olympiads survived the Olympics themselves. The
Chronicon Paschale dates events by Olympiad down to the 352nd Olympiad (AD628). == Modern Olympics ==