The presence of the Genoese in the Aegean after the Fourth Crusade in 1204. The Genoese settlements in the Levant and the role of the Byzantines in the establishment of their settlements in the area.  

After the fall of Constantinople to the Latins of the fourth crusade, the Republic of Genoa suffered a considerable defeat in the political and diplomatic arena. Venice was greatly favoured by the new status quo in the former Byzantine lands and was given control of the sea routes in the Aegean by the Partitio Romanie. Venice established colonies and centres of commercial and strategic importance such as Crete and the island of Naxos that greatly facilitated their main objectives against their rivals in the Levant. On the contrary the Genoese experienced the expulsion from the Romania losing their centres of trade including the area of Pera allocated to them with commercial privileges ceded by the Emperor himself. Genoa attempted to question the Venetian supremacy in the area with a series of war expeditions in Corfu and Crete organized by Leo Vetrano and Enrico Pescatore respectively. By 1218 with the convention signed in that year, Genoa had managed to restore its rights in the Empire of Constantinople.

However, the presence and hegemony of Venice in the area assisted by the established political situation (the Latin Empire of Constantinople) had greatly inhibited the commercial activities of the Genoese that had lost ground in the naval arena of the Aegean. The Genoese also attempted to start negotiations with the Nicean Empire and the despotate of Epirus and were eventually assisted and directed by the troops of Ioannis Vatatzes to annex Rhodes, an essential port of call in the eastern  Mediterranean. The treaty of Nymphaeum and the concessions made by Michael VIII Paleologos re-established the Genoese in the area although the Byzantine promises were not entirely fulfilled. The agreement between the two sides included the allotment of trading outposts under the sovereignty of the Emperor-Basileus, in Constantinople, Smyrna, Cassandria Crete, Negroponte (Euboea), Chios and Mytilene.

By the end of the first half of the 14th century the antagonism for the division of the Aegean waters into zones of influence between Venice and Genoa had culminated. The Venetians dominated the sea routes as far as the straits of the Dardanelles and the west areas encompassing the Dalmatian coasts and the Ionian Islands. On the contrary Genoa, had under its control the Eastern coasts and islands of the Aegean that constituted another route for accessing the capital and the centres of commerce in Anatolia. The Genoese occupation in the area of the eastern Aegean had already started to become well established. It was enhanced by the political and military incompetence of the Byzantines that rendered them tolerant to the presence of the Latins in the Balkan Peninsula and the Western coasts of Asia Minor that not many years ago constituted some of the most undisputable Byzantine territories. The coexistence of Latins and Greeks can be considered as inevitable based on the immediate objectives of the Byzantines for political survival that followed the decadence between the 11th-13th centuries that deteriorated with the detrimental effects that the Fourth Crusade had on the Empire and the permanent establishment of the Ottoman Turks in Asia Minor.