The Republic of Ancona was a medieval commune and maritime republic notable for its economic development and maritime trade, particularly with the Byzantine Empire and Eastern Mediterranean, although somewhat confined by Venetian supremacy on the sea. It enjoyed excellent relations with the Kingdom of Hungary, was an ally of the Republic of Ragusa, and maintained good relations with the Ottoman Empire. All these relationships enabled it to serve as central Italy's gateway to the Orient.

The maritime republics, also called merchant republics, were Italian thalassocratic port cities which, starting from the Middle Ages, enjoyed political autonomy and economic prosperity brought about by their maritime activities. The term, coined during the 19th century, generally refers to four Italian cities, whose coats of arms have been shown since 1947 on the flags of the Italian Navy and the Italian Merchant Navy: Amalfi, Genoa, Pisa, and Venice. In addition to the four best known cities, Ancona, Gaeta, Noli, and, in Dalmatia, Ragusa, are also considered maritime republics; in certain historical periods, they had no secondary importance compared to some of the better known cities.