The Olympic Games ( , "Olympiakoi Agones") were a series of athletic competitions among representatives of city-states and one of the Panhellenic Games of Ancient Greece. They were held in honor of Zeus, and the Greeks gave them a mythological origin. The first Olympics is traditionally dated to 776 BC. They continued to be celebrated when Greece came under Roman rule, until the emperor Theodosius I suppressed them in 394 AD as part of the campaign to impose Christianity as the state religion of Rome. The games were held every four years, or olympiad, which became a unit of time in historical chronologies.