| In the 5th c. BC, los was a member of the | | | | refuge, and the inhabitants frequently had to |
| Athenian Confederacy, in contrast with the | | | | withdraw into the hills, to the Kastro, in order to |
| neighbouring islands of Pholegandros, Santorini, | | | | defend themselves. |
| Anaphi, Milos, and Kimolos, which were allies of the | | | | A major change in the history of los was marked |
| Spartans, and founded the Island League. There | | | | by the capture of Constantinople in 1204 by the |
| followed the wars against the Persians (battle of | | | | Franks, and the appearance in the Cyclades of |
| Marathon in 490 BC, battle of Salamis in 480 BC), | | | | the Venetian Marco Sanudo. Sanudo captured |
| the defeat of the Persians, and the Peloponnesian | | | | Naxos and proceeded to take most of the |
| War (431 BC - 404 BC) -the conflict between | | | | Cycladic islands, including los, in 1207, founding the |
| Athens and Sparta, from which the latter | | | | Duchy of Naxos, or Duchy of the Archipelago. A |
| emerged victorious. | | | | campaign by the Italian admiral Licario in alliance |
| Later, in 338 BC, Philip ll, king of Macedonia and | | | | with the Byzantines successfully detached los and |
| father of Alexander the Great, defeated his | | | | some other islands from the Venetians in 1269. |
| adversaries at the battle of Chaironeia and united | | | | The change was short-lived, however, and in |
| all the Greeks against the common foe, the | | | | 1296, the Venetian Domenico Sciavi expelled the |
| Persians. los thus passed under the suzerainty of | | | | Byzantines and made himself master of los. From |
| the Macedonians and, after the death of | | | | the Sciavi dynasty, the island later passed into the |
| Alexander the Great, of his successors, the | | | | hands of the Crispi, who were Dukes of Naxos, |
| Ptolemies. | | | | ending with Marco Crispo I, who founded his own, |
| In the 1 st c. BC los was conquered by the | | | | independent dynasty. About 1400, Crispo repaired |
| Romans who reduced it to the status of place of | | | | the Kastro on top of the hill overlooking Chora, in |
| exile and condemned it to obscurity. During the | | | | order to defend the inhabitants from pirate raids. |
| Byzantine period, too (4th c. AD onwards), which | | | | The last ruler of los before its capture by the |
| lasted for over 800 years, los enjoyed no better | | | | Turks was the Venetian Aloysios Pizani, who |
| fortune. There were frequent raids by pirates, | | | | married a daughter of the Crispi and received the |
| who used the famous harbour on the island as a | | | | island as his dowry. |