Ithaca dating service
The sophist Hippias was the first writer to publish a list of victors of the Olympic Games, and by the time of Eratosthenes, it was generally agreed that the first Olympic games had happened during the summer of 776 BC.
The combination of victor lists and calculations from 776 BC onwards enabled Greek historians to use the Olympiads as a way of reckoning time that did not depend on the time reckonings of one of the city-states.
(See Attic calendar.) The first to do so consistently was Timaeus of Tauromenium in the third century BC.
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 century BC are very unreliable.
Some winners were recorded though, until the last Olympiad of 393AD.
In 394, Roman Emperor Theodosius I outlawed the games at Olympia as pagan.
A modern Olympiad refers to a four-year period beginning January 1 of a year in which the Summer Olympics are due to occur.
The first modern Olympiad began in 1896, the second in 1900, and so on (the 31st began in 2016: see the Olympic Charter).
Therefore, the games would have been held in July/August of 220 BC and held the next time in July/August of 216 BC, after four olympic years had been completed.However, the IOC does not seem to make an official distinction between Olympiads for the summer and winter games, and such usage particularly for the Winter Olympics is not consistent with the numbering discussed above. However, it indicates these quadrennia in calendar years, starting with the first year after the Summer Olympics and ending with the year the next Olympics are held.This would suggest a more precise period of four years, but the 2001–2004 Quadrennium would then not be exactly the same period as the XXVIIth Olympiad.The first poster to announce the games using this term was the one for the 1932 Summer Olympics, in Los Angeles, using the phrase: Call to the games of the Xth Olympiad Note, however, that the official numbering of the Winter Olympics does not count Olympiads—- it counts only the Games themselves.For example: Some media people have from time to time referred to a particular (e.g., the nth) Winter Olympics as "the Games of the nth Winter Olympiad", perhaps believing it to be the correct formal name for the Winter Games by analogy with that of the Summer Games.