The Aegean island Columbus visited while it was ruled by Genoa was Chios.
Chios lay on important trade routes in the eastern Aegean and was under Genoese control during the period relevant to Columbus’s early maritime career. Genoese forces took control in 1346 through the Maona di Chio e di Focea, a chartered commercial company. Genoese administration continued until the Ottoman conquest in 1566.
The island was commercially valuable for products including mastic, alum, salt, and pitch. Columbus is associated with Chios in the 1470s, before his later voyages under the Spanish Crown. His time there fits the broader pattern of travel through Genoese and Portuguese trading networks that exposed him to Atlantic and Mediterranean commerce.
Rhodes, Crete, and Cyprus were also prominent Mediterranean islands, but they do not fit this specific clue. Chios is especially distinctive because its Genoese period lasted for more than two centuries and connected the island directly to Columbus’s Genoese background.