During the 5th century BCE, the main livelihood for the island's inhabitants was fishing.
Apollo, the Greek god of the sun and music, was deemed the island's protector. A temple dedicated to him was located within the Akropolis of Karthaia on the eastern shore of the island, and therein were recorded the public laws.
In addition to this, Aphrodite was especially venerated on the island, as she was believed to oversee all civic matters, and protect the local magistrates' positions. A shrine dedicated to her was located at the tip of jut of land on the eastern shore of the island.
Around the time of the Peloponnesian War, the main city of the island, Koressia, was assaulted by pirates who burned the city down and claimed it. After establishing a presence on the island, the pirates discovered that the population was drastically dwindling due to a shortage of food. To rectify this crisis, they went to the extremes of forcing all inhabitants older than sixty to commit suicide by drinking concoctions of deadly hemlock. While this ensured the survival of the rest of the population, it left behind a foul stench of death in the island's interior.
The acting Athenian leader of the Pirate Islands was driven from his home in Poiessa Village. He took refuge in the Koressia Fort down the western shore of the island, while Xenia, called the 'pirate queen', took up residence in Koressia's Temple of Athena Nedousia.
The island of Keos was made up of four regions:
- Assassin's Creed: Odyssey – Worlds: Paradise Islands, Pirate Island. Ubisoft. Accessed 18 June 2018.
- Assassin's Creed: Odyssey – Keos: Akropolis of Karthaia
- Assassin's Creed: Odyssey – Keos: Shrine of Aphrodite
- Assassin's Creed: Odyssey
- Assassin's Creed: Odyssey – Heart of Stone