Excavations on Kos island indicate that the island was inhabited in the early Bronze Age, between 2900 and 2100 B.C., by a succession of ancient people such as the Pelasgians, Carians (who called the island "Kouris" or "Karis"), Leleges, Achaians end Phoenicians. Evidence has also been found for a strong Minoan and Mycenaean influence on Kos island.
Together with the surrounding islands, Kos islandt ook part in the Trojan War, sending Pheidippos and Antiphos, sons of King Thessalos, with 30 deep hulled ships.
After the 10th century BC, the Dorians occupied Kos. This led gradually to the growth of the communities (demoi). The island's first capital was Astypalaia on the southwest side, which experienced great cultures development.
During the 7th and 6th centuries B.C., Kos, together with the cities of Knidos and Halicarnassos in Asia Minor, and lalysos, Kamerios and Lindos on Rhodes, formed the Doric Hexapolis, a league with political, economic and religious concerns.
Kos islandsuffered greatly as a result of the Persian wars (500-478 BC). After the battle of Mykale (479 BC), it became independent and joined the confederation of Greek states under theleadership of Athens.
Among the distinguished persons born in Kos islandduring the classical period were Epicharmos, founder of the Sicilian Comedy and Hippocrates, Father of Medicine (460-377 BC). Hippocrates, descendant of Asclepiad priests, founded his own School which placed the science of medicine at the service of man. The Hippocratic Oath stands out among the great doctor's 59 works as a masterpiece of ethical greatness, his immortal legacy to doctors all over the world. One of the most remarkable archaeological sites on the island is the Asklepion, possibly the best hospital of its time. Its famous spa, with running mineral waters, was used to treat skin diseases. Also surviving the millennia is the plane tree, under the shade of its rich foliage Hippocrates used to tutor his students.