The archaeologists speak of early human settlement on the island of Kea in the bay of St. Nicholas, while Neolithic period settlements in cape Kefala have been identified. From the Bronze Age we have the organized and fortified village of Agia Irini. During historical times, Kea was considered an Ionic island and it was the only island in the Cyclades which, according to ancient geographers, had four autonomous and independent cities. During the Archaic period (7th-6th century BC) those were Ioulis, Karthea, Korrisia (or Korissos) and Piiessa. These four cities, the most important of which was Karthea, as numismatic evidence testifies, bore a great financial and moral growth. Aristotle, in fact, wrote a separate book about the state of the residents of Kea. The poets Simonides senior and his grandson Simonides Leoprepou in the mid-3rd century BC originated from here. Simonides the younger just before the Peloponnesian war and Bacchylides in the middle of the 5th century BC as well. There is a list of sophists and philosophers like Pythokleidis, Theramene, Agnonos and the peripatetic philosopher Ariston who originated from Kea. This is the place of origin of the ancient doctors Pantheidis, Medias and Erisistratos.
According to an ancient tradition that has been recorded by Strabo, the custom of old men over 60 years old committing suicide using hemlock prevailed in Kea. The “Kion Nomimon” (lawful in Kea) as it was known, that was said to have been established during the siege of the island by the Athenians. The citizens then had voted in favour of the voluntarily death of the elder, in order for the very limited food of the besieged to suffice. The extension of the siege as a result compelled the Athenians to solve the naval embargo of the island.
The residents of the island participated with two galleys and two pentikontoros in the naval Battle of Artemisium in 480 BC, and according to an inscription of a statue in ancient Olympia, they took part in the naval Battle of Salamis. The presence of a booming economy on the island is referred at that time due to the exploitation of iron mines and a mineral substance called minium that was in great demand in Athens as a medicine and as a colour for writing and painting. I was also of great use in the long-term maintenance of Athenian ships.
During the Peloponnesian War, the Keans fought with the Athenians and in 413 BC they took part in the Sicilian campaign. The Tetrapolis of Kea joined the second Athenian Leaguein 377-376 BC, and in 338 BC it fought in the battle of Chaeronea with the Athenians against the Macedonians. During the Hellenistic period it became part of the Common of the Islanders and became a bone of contention among the successors of Alexander the Great, resulting in the four cities of the island ceasing being autonomous. In Roman times Kea was visited by Pompey when travelling to Asia, and Cicero on his way to Cilicia. After Caesar's assassination, Antony gave Kea to the Athenians in 42 BC. The dependence on Athens continued during the reign of Hadrian, while in 212 AD the island by order of Caracalla returned to the Romans.
It is referred to as a meeting place of Pope Constantine and the Patrician Theophilus in 770. After the capture of Athens by the Franks in 1204, the Bishop of Athens, Michael Akominatos, resided on the island for 15 years. During the Rule of Franks it was a fief successively for the houses of Gizi, Giustiniani, Dacoroni, Micheli, Premarini and Gozzadini. At that time the island was known as Gea, since on the Venetian maps it is reported either as Cea or Zea. During the reign of the emperor Michael VIII Palaiologos the island has been recaptured by the Byzantine admiral Likarios. In 1298, after the war between the Byzantines and Venetians came to the families of the Venetians again. At that time, Kea was safe hideout for pirates and the residents used to help them. Because of this reason the Turks called the island Mourdettadhase, that is the island of the renegades.
In 1537 the fleet of Barbarossa conquered the island and many of the residents were taken into slavery. In 1566 the pasha Piali occupied Kea which became part of the Duchy of the Aegean Sea under the tax jurisdiction of the Jewish banker Joseph Nazis. At that time we have the settlement of Arvanites, who quickly merged with the locals in Kea. In the Turkish- Venetian war, in 1665, the island suffered a lot, since the residents were obliged to pay Harac to the Turks and a tribute to the Venetians.
The domination of the Turks was interrupted in 1170-1774.The port of the island became the base of the legendary Lambros Katsonis in 1789. At the area Laimos tis Kokkas, the harbour entrance, the heroic sea-warrior escaped and saved his fleet of ships passing through a narrow strip of land into the open sea.