Once every four years, men from all over Greece came to compete in a great athletic festival in Elis, in western Greece (The men wouldn't let women compete). This was called the Olympic games because the place was called Olympia. The Olympic Games were a religious festival to honor the Greek gods Zeus and Hera.
The temple of Hera in Olympia, Elis, Greece
We don't know when men first began celebrating the Olympic Games, but they were certainly already doing it in the time of Homer, by 776 BC. And they were celebrated from then on, every four years without fail, until people converted to Christianity and the Roman Emperor Theodosius banned the games in 393 AD. That's more than a thousand years! The games were so regular that people used them to date by. They would say, I was born in the second year of the twenty-fourth Olympiad (starting from 776 BC). Can you figure out what year that would be in our reckoning?
When it was time for the games, the rulers of Elis sent out messengers all over Greece and to the Greek colonies around the Black Sea and the Mediterranean. They declared a truce throughout the Greek world for a month. No matter who you had a war with, you had to stop the war and let their athletes and performers go through your city-state safely to get to the Olympic Games. Each city-state paid for a few athletes from their city to travel to Elis. But if you had ever been a slave, or if you had ever done anything against the gods, then you couldn't be in the Olympics. And, the men had to swear that they had already trained for at least ten months. This meant that only men who were pretty rich could be in the Games, so they could afford to take so long off work, and also pay a trainer.