During the twenties-forties years of the XV-th century the Theodorits recaptured from Genovese the important seaside fortresses and undermined the Italian trade in the Black Sea region. The port of Avlita (now the territory of Sevastopol) that belonged to the Theodorits became one of the largest trade centers on the Silk Road.
The governors of Theodoro were relatives the Byzantine and Trebizond Emperors, Moscow grand princes, the rulers of Crimean khanate and Moldavia.
In the 1425-th under the will of Byzantine Emperor Manuel II the provinces of Tavrika were passed to his fourth son Constantine Dragash, later – the last Byzantine Emperor Constantine XI, who was perished during the Turkish seize of Constantinople.
After the Turkish seizure of Constantinople (1453), Mistras (1460) and Trebizond (1461) Theodoro stayed as the last state of “Byzantine world” that maintained the political independence. Byzantines remained in Crimea for 22 years after the downfall of Empire. In 1475 the military expedition under the command of Grand Vizier Gedik Ahmet was organized into Crimea. Genoese and Tatars capitulated at once. On the peninsula only Theodorits offered the adequate resistance to theTurks. In spite of the tremendous numerical superiority Turks seized Mangup for t five months. At last at the end of the year they captured the town. The capital of Theodoro principality had fallen. In the Northern part of the Black Sea region the three hundred years epoch of the Turkish rule began.