Both republics had merchant colonies within the city – Leonkastron and the former "Venetian castle" – that played a role to Trabzon similar to the one Galata played to Constantinople (modern Istanbul). Trabzon formed the basis of several states in its long history and was the capital city of the Empire of Trebizond between 1204 and 1461. During the early modern period, Trabzon, because of the importance of its port, again became a focal point of trade to Persia and the Caucasus.