Legend has it that the origin of the name Ios comes from the Ionian settlement and that the island was already inhabited during the early Cycladic period. The most important prehistoric settlement that was found on the island is located upon a hill to the entrance of the port.
Ios is also the island where many historical reports attest that the great epic poet Homer was buried. According to Herodotus, the last resting place of Homer is a ruin in Plakotos, situated in the northern part of the Cyclades Island, called Homer's tomb; a myth that Ios inhabitants keep alive with pride.
The history of Ios is similar to the rest to the Cycladic islands. In ancient times, Ios joined the Athenian Alliance and in the beginning of the 13th Century came under the Venetian rule. In the 15th Century, it came under the authority of the Venetian family of Crispus, which fortified the previous castle (Castro) of Chora, whose ruins are visible up until today. In 1537, the island suffered from pirate raids and later, Ios fell to the hands of Ottomans.
During the Greek War of Independence against the Turkish domination. Ios was liberated and became independent in 1829, forming part of the Modern Greek State.