The origins of the games at Olympia are rooted in legends - the most predominant relating to the god Pelops , revered in the region before his eclipse by Zeus, and to Hercules ( Herakles ), one of the earliest victors. Historically, the contests probably began around the eleventh century BC, growing over the next two centuries from a local festival to the quadrennial celebration attended by states from throughout the Greek world.

The impetus for this change seems to have come from the Oracle of Delphi , which, with the local ruler of Elis, Iphitos , and the Spartan ruler Lykourgos , helped to codify the Olympic rules in the ninth century BC. Among their most important introductions was a sacred truce , the Ekeheiria , announced by heralds prior to the celebrations and enforced for their duration. It was virtually unbroken throughout the games' history (Sparta, ironically, was fined at one point) and as host of the games, Elis, a comparatively weak state, was able to keep itself away from political disputes, meanwhile growing rich on the associated trade and kudos.

From the beginning, the main Olympic events were athletic. The earliest was a race over the course of the stadium - roughly 200m. Later came the introduction of two-lap (400m) and 24-lap (5000m) races, along with the most revered of the Olympiad events, the pentathlon . This encompassed running, jumping, discus and javelin events, the competitors gradually reduced to a final pair for a wrestling-and-boxing combat. It was, like much of these early Olympiads, a fairly brutal contest. More brutal still was the pancratium , introduced in 680 BC and one of the most prestigious events. Pancratium contestants fought each other, naked and unarmed, using any means except biting or gouging each others' eyes; the olive wreath had on one occasion to be awarded posthumously, the victor having expired at the moment of his opponent's submission. Similarly, the chariot races , introduced in the same year, were extreme tests of strength and control, only one team in twenty completing the seven-kilometre course without mishap.

The great gathering of people and nations at the festival extended the games' importance and purpose well beyond the winning of olive wreaths; assembled under the temporary truce, nobles and ambassadors negotiated treaties, while merchants chased contacts and foreign markets. Sculptors and poets , too, would seek commissions for their work. Herodotus read aloud the first books of his history at an Olympian festival to an audience that included Thucydides - who was to date events in his own work by reference to the winners of the pancratium .

In the early Olympiads, the rules of competition were strict. Only free-born male Greeks could take part, and the rewards of victory were entirely honorary: a palm, given to the victor immediately after the contest, and an olive branch, presented in a ceremony closing the games. As the games developed, however, the rules were loosened to allow participation by athletes from all parts of the Greek and Roman world, and nationalism and professionalism gradually crept in. By the fourth century BC, when the games were at their peak, the athletes were virtually all professionals, heavily sponsored by their home states and, if they won at Olympia, commanding huge appearance money at games elsewhere. Bribery became an all too common feature, despite the solemn religious oaths sworn in front of the sanctuary priests prior to the contests.

Under the Romans , predictably, the commercializing process was accelerated. The palms and olive branches were replaced by rich monetary prizes, and a sequence of new events was introduced. The nadir was reached in 67 AD when Emperor Nero advanced the games by two years so that he could compete in (and win) special singing and lyre-playing events - in addition to the chariot race in which he was tactfully declared victor despite falling twice and failing to finish.

Notwithstanding all this abuse, the Olympian tradition was popular enough to be maintained for another three centuries, and the games' eventual closure happened as a result of religious dogma rather than lack of support. In 393 AD Emperor Theodosius, recently converted to Christianity, suspended the games as part of a general crackdown on public pagan festivities. This suspension proved final, for Theodosius's successor ordered the destruction of the temples, a process completed by barbarian invasion, earthquakes and, lastly, by the Alfi�s River changing its course to cover the sanctuary site. There it remained, covered by seven metres of silt and sand, until the first excavation by German archeologists in the 1870s.