Which cities controlled the main trade routes in Europe and communications with the East?

In the early Middle Ages, Constantinople was such a city; trade routes from Europe to Asia passed through it. During the era of the Crusades, in the XII-XIII century, control over the trade routes passed to the Italian trading republics – Venice, Genoa and Pisa, especially to the first two. In the XIV century, Constantinople and Byzantium were in decline, and the Genoese, for example, controlled the southern coast of Crimea. In 1453, after the fall of Constantinople, it was renamed Istanbul and he began to control the trade route to Asia (by 1475 the Turks took possession of the southern coast of Crimea and Trabzon), and the Europeans began to search for a sea route to India.