Ios’ history cannot differ much from that of the other islands of the Cyclades. The first habitants were a tribe called Kareans
(3200 - 2700 BC) that hailed from Asia Minor. According to the most recent studies and excavations, after the arrival of the said tribe from Asia Minor, a very important Cycladian civilization flourished in Ios for many centuries (2700 - 2300 BC). This was followed by the Minoan thalassocracy in the Aegean sea. The Minoan civilization
(2000 - 1500 BC) and the volcanic eruption of Thira, influenced the historic development of the island decisively. Then arrived the Achaeans, who left important elements of their domination, of which the most impressive is the Cyclopian wall that can still be seen across the city hall.
In later times, the Phoenicians ruled the roost. Being great mariners, they brought many trees from other countries, which they transplanted in Ios. The cultivation of palm trees was so important, that coins from this era depict a palm tree on the one side and Homer on the other.

Homer, the legendary poet of antiquity, is connected with Ios. This is obvious from the reports that exist about the island in many ancient opuses. In one of these, Ios is referred as one of the seven cities that assert the title of Homer’s birthplace. Of course, this is mainly due to Homer’s grave in Ios, in the area of Plakoto.
Many ancient writers and historians have made researches on Homer’s grave in Ios. Among them are famous personalities like the historian Strabo, the poet Alkaeos, Pliny and Pausanias.   According to works from the 2nd century AD, Homer came in Ios when, during a trip from Samos to Athens, his boat was thrown in the shores of the island because of a terrible storm. It is said that he was so exhausted, that he died there. Another scenario is that Homer had met some fishermen there, who posed a conundrum that he was unable to solve.

At the end of the 10th century BC, Ionians dominate the island. During the 6th century BC, Ios is part of the Athenian League. Later, during the predominance of Philip II, Ios bows to the Macedonian crown. Afterwards it was dominated by the Ptolemaic Dynasty and then by the Roman Empire. During the Byzantine Empire, Ios sank into oblivion. For a while, Ios was a place of banishment.

In 1207, Ios has the same fate with its vicinal islands, which were conquered by the Dukedom of Naxos, under the leadership of Marcus Sanudus. In 1269, the Italian Admiral Licarius, who had joined forces with the Eastern Empire, conquered Ios. In 1296 the Venetian rule dominates the island, after the defeat of the Byzantine army by Dominicus Skiabbi. Then ruled the Dynasty of Crispi. In 1397 AD, Marcus Crispi built the castle of the island, in order to protect the population from the pirates. There are still remains of this castle.

Finally, in 1537, Ios is conquered by the infamous pirate Barbarossa and the Turks. The Turks did not inhabit the island immediately, but burdened the population with unbearable taxes. In 1558, Turkish pirates invaded Ios, pillaged the island and transported the inhabitants as slaves to the Oriental slave markets. Hence, the island was depopulated for more than 20 years.
In 1668, while Ios was still under the Turkish rule, French warriors defeated the Turkish fleet of Kapudan Pasha in “Malta Minor”. The Turks called Ios that way, because of the security that offered its natural harbor. Later, this area was called “Bourloto”.
Afterwards, there was the Russian rule (1770 - 1774) that ended with the Treaty of Kiutsuk Kainardji. With this treaty, special privileges were granted to the Cyclades, mainly concerning commerce and seafaring, which flourished until 1821, the period that signaled the beginning of the Greek Revolution.

During this period, Ios participated to the Revolution, thanks to the great Spyridon Valettas, member of the secret “Friendly Society”, who stood out in the Revolution and later became the first Minister of Education of the free Greek State. Spyridon Valettas was a great benefactor for Ios.

At the following years, Ios shared the same fate with the rest of Greece, especially the Cyclades.