Eastern Aegean island, lying west of the peninsula near Izmir (Smyrna) in western Anatolia and north of the Dodecanese;
- A nome (department) in Greece.
It was generally Byzantine before 1204, though the Arabs held it in the 670s until they raised the siege of Constantinople, and the Seljuk Turkish Emir of Izmir possessed it in the later part of the 11th century.
Chios belonged to the Latin Empire in 1204, was recovered by the Greek Empire of Nicaea in 1225, lost to a Genoese noble in 1304, but became Byzantine again in 1329 until Genoa took it over in 1346.
Genoese rule lasted until 1566, when Chios became the last of their Aegean possessions to fall to the Turks, with whom it remained until the Greek victories of 1913.
With some of the small islands nearby it forms a nome (department), which belonged to the Aegean Islands region until 1987 and since then to the North Aegean region.