The conquest of the Aegean islands
Surviving information as regards the conquest of the Aegean islands is contradictory. One hypothesis is that the islands had been conquered during a combined undertaking of Venetian nobles under the guidance of Marco I Sanudo, nephew of the doge of Venice. In 1207, Sanudo established the duchy of the Aegean, which included Naxos, the capital of the duchy, Paros, Antiparos, Milos, Ios, Amorgos, Kythnos, Sikinos, Sifnos, Kimolos and Syros. The rest of the Aegean islands were distributed to his comrades-in-arms. More specifically, Marino Dandolo conquered Andros, the Ghisi received Tinos, Mykonos, Skyros, Skopelos, Skiathos and Serifos, Leonardo Foscolo received Anafi, G. Barozzi conquered Santorini, Quirini received Astypalaia and Amorgos, Andrea Cornaro received Karpathos and Marco Venier acquired Kythera.
In 1227 Marco I Sanudo died and was succeeded by his son Angelo (1227-1262). In 1240 the duchy came under the rule of the prince of Achaia, Geoffrey II de Villehardouin. The duchy was strongly undermined during the time of Marco II Sanudo (1262-1303) after the dissolution of the Latin Empire of Constantinople. In 1265, by virtue of the Venetian-Byzantine treaty, Venice waived its right to the islands that belonged to the Latin Empire of Constantinople. In 1276 the Italian knight of Karystos, Licario, who was under the service of Michael VIII Palaiologos, conquered Skopelos, Skiathos, Skyros and Limnos, whereas Santorini, Ios, Sifnos, Sikinos, Folegandros and Astypalaia were conquered by the Byzantines. Only the Sanudi and the Ghisi remained in the Aegean. Between 1296 and 1303 Marco II Sanudo recovered a large part of the duchy. After the death of Geoffrey II de Villehardouin, in 1278, Sanudo made fealty to Charles I of Anjou.
The crisis and collapse of the Frankish rule
In early 16th century, the conditions that had ensured the expansion of the Latin rule in the Cyclades ceased to exist. The Venetian fleet lost its superiority in the Aegean and during the Turkish-Venetian war between 1499 and 1503 the Ottoman powers invaded many islands with destructive consequences. The pacification of 1503 did not give an end to the activity of the Muslim pirates, who continued to plague the economy of the islands. Moreover, during the first decades of the 16th century, serious dynastic problems had emerged, whereas the already bad health of the population, mainly due to the water, which was unfit to drink, deteriorated from the contagious diseases that appeared in East Mediterranean. Lastly, the abuses of the governors of the islands gave rise to complaints by the inhabitants, who requested that the ruler change, since they often felt that the enfeebled prestige of the Venetian state did not cover them.
After a period of Turkish rule (1537-1566), during which the institutions of the Frankish conquest had become effete, the duchy was conclusively dissolved after 359 years of existence. The sultan Selim II conceded the administration of the islands to his favoured Joseph Naci, a Jewish adventurer of Portuguese origin, who maintained the rule up to 1579. Then the Cycladic islanders requested the reinstatement of the Latin authorities. Ultimately, however, the islands were annexed to the Ottoman Empire and a sadzak bey together with a kades assumed the governance. A year later the islands received privileges from Murat II, which were ratified sixty years later. However, a small Latin dynasty, the Gozzadini, had been reinstated in 1571 in Sifnos and was maintained for forty years approximately, perhaps due to the fact that this family came from Bologna and not from Venice. Still, Sifnos, in its turn was incorporated into the Ottoman Empire in 1617.