History

The Olympians, Also known as Gargareans, Thalarions, and colloquially, Manazons, were created by Zeus from the dead heroes of the ancient times. They were made to be the counterpart to the Amazons, whom Zeus has deemed have failed in their quest to bring peace.
Like Themyscira, the Olympians were given an island home of Thalarion, an island with a city of crystal, so that they would have no secrets, and a river of gold, so that they would feel no jealousy towards the outside world. From this island they got their name, Thalarions.
The leader of the Olympians was Jason, an honorable and brave man. But like Wonder Woman, Zeus gave them a prime champion, and from the heart of God Kane Milohai (Whom Zeus killed) he created Achilles, the Olympian. Achilles, made by Zeus but adopted by Jason, would become their king.
 
Soon the Thalarions began to spread their message of peace throughout the world, by storming the UN building and declaring the world leaders failures and attacking missile bases. This drew the attention of Wonder Woman who briefly fought Achilles, finding him a match.
 
Soon, however, treachery struck. Euphemus, Jason's second in command, and the son of Poseidon, was a follower of Ares, and under his orders, commanded the sea creatures to attack Thalarion and Themyscira. The Olympians and Amazons were forced to join forces to fight off the attack, and ultimately kill Ares.
After this battle, Zeus makes Achilles king of Themyscira instead of Hippolyta, making Thalarions de facto in charge of the Amazons. Naturally, the Amazons don't like this one bit. Achilles, in need of allies among the Amazons, asks Alkyone, the captain of Hippolyta's guard, to be his wife. 
This proves to be a mistake, as Alkyone has only one thing in mind: destroying Wonder Woman. To this end she summons a demon named Cottus, against which the Amazons and Olympians are forced to unite once more. With Cottus defeated and Alkyone and her circle dead, it seems peace will last between the two races.