Known as "Ofioussa" (having snakes) and "Pityoussa" (having pine trees) in antiquity, during the medieval age the island was ruled by a number of external powers and has also been known as Scio (Genoese), Chio. The capital has also been known as "Castro" or "Kastron" (Καστρον; meaning castle).
Archaeological research on Chios has found evidence that the island has been inhabited since at least the Neolithic era. The primary sites of research for this period have been cave dwellings at Hagio(n) Galas, in the north, and a settlement and accompanying necropolis in modern-day Emporeio at the far south of the island. Scholars lack information on this period. The size and duration of these settlements have therefore not been well-established.
The British School of Athens excavated the Emporeio site in 1952–1955, and most current information comes from these digs. The Greek Archaeological Service (G.A.S.) has also been excavating periodically on Chios since 1970, though much of its work on the island remains unpublished.
The noticeable uniformity in the size of houses at Emporeio leads some scholars to believe that there may have been little social distinction during the Neolithic era on the island. The inhabitants apparently all benefited from agricultural and livestock farming.
It is also widely held by scholars that the island was not occupied by humans during the Middle Bronze Age (2300–1600), though researchers have recently suggested that the lack of evidence from this period may only demonstrate the lack of excavations on Chios and the northern Aegean.
By at least the 11th century BC the island was ruled by a kingdom/chiefdom, and the subsequent transition to aristocratic (or possibly tyrannic) rule occurred sometime over the next four centuries. Future excavations may reveal more information about this period. 9th-century Euboean and Cypriote presence on the