During the Final Neolithic (over 5,000 years ago), Andros had a fortified village on its west coast, which archaeologists have named Strofilias, after the plateau on which it was built. Strofilas was related to the "Attica-Kephala" culture, and predates the Cycladic culture of the Bronze Age. It was an important maritime center and one of the earliest examples of fortification in Greece.
It is notable for rock carvings on its walls, which include animals such as jackals, goats, deer, fish and dolphins, as well as a depiction of a flotilla of ships.
The island in ancient times contained an Ionian population, perhaps with an admixture of Thracian ancestry. Though originally dependent on Eretria, by the 7th century BC it had become sufficiently prosperous to send out several colonies, to Chalcidice (Acanthus, Stageira, Argilus, Sane).
The ruins of Palaeopolis, the ancient capital, are on the west coast; the town possessed a famous temple, dedicated to Dionysus. In 480 BC, it supplied ships to Xerxes and was subsequently harried by the Greek fleet.
Though enrolled in the Delian League it remained disaffected towards Athens, and in 477 had to be coerced by the establishment of a cleruchy on the island; nevertheless, in 411 Andros proclaimed its freedom, and in 408 withstood an Athenian attack. As a member of the second Delian League it was again controlled by a garrison and an archon.
In the Hellenistic period, Andros was contended for as a frontier-post by the two naval powers of the Aegean Sea, Macedon and Ptolemaic Egypt. In 333, it received a Macedonian garrison from Antipater; in 308 it was freed by Ptolemy I of Egypt. In the Chremonidean War (266-263) it passed again to Macedon after a battle fought off its shores.
In 200, it was captured by a combined Roman, Pergamene and Rhodian fleet, and remained a possession of the Kingdom of Pergamon until the dissolution of that kingdom in 133 BC, when it was granted to Rome.