According to mythology, Folegandros took its name from Minoas son, who was leader of the Cretans, the first settlers of the island. In antiquity it was widely known by the name "Sidira" (Iron) because of its rocky ground. It was also called "Polikandros", a name which comes from the Phoenician. After the Cretans, the island was inhabited by the Dorians who built their town east of the present one. The island played an important part in ancient years. In the 13th century, Marco Sanudo founded the Duchy of the Aegean and built the impressive castle. Folegandros fell to the Turks at the same time as the rest of the Cyclades, after it had been pillaged and massacred by pirates. In 1830 it was liberated by the Treaty of London.