The conquest of the Crimea by the Tatar khans in the thirteenth century and the gradual extension of their sovereignty to the Principalities of Kiev and Moscow brought the old center of Judaism in the Tauris region in close contact with its offshoots in various parts of Russia. Kiev enters into regular commercial intercourse with Kaffa (Theodosia) on the Crimean sea-shore. Kaffa becomes during that period an international emporium, owing to the Genoese, who had obtained from the Tatar khans concessions for Kaffa and the surrounding country, and had founded there a commercial colony of the Genoese Republic. The Crimean Peninsula was joined to the world commerce of Italy, and merchantmen were constantly ploughing the seas between Genoa and Kaffa, passing through the Byzantine Dardanelles. Italians, Greeks, Jews, and Armenians flocked to Kaffa and the adjacent localities on the southern coast of the Crimea. The Government of the Genoese Republic time and again instructed its consuls who were charged with the administration of the Crimean colony to observe the principles of religious toleration in their attitude towards this heterogeneous population. If the testimony of the traveler Schiltberger, who visited the Crimea between 1394 and 1427, may be relied upon, there were in Kaffa Jews "of two kinds," evidently Rabbanites and Karaites, who had two synagogues and four thousand houses, an imposing population to judge by its numbers. The great crisis in the history of Byzantium--the capture of Constantinople by the Turks--affected also the Genoese colony in the Crimea. The Turks began to hamper the Genoese in their navigation through the straits. In 1455 the Genoese Government ceded its Kaffa possessions to the Bank of St. George in Genoa. The new administration set out to restore order in the colony and establish normal relations between the various races inhabiting it; but the days of this cultural oasis on the Black Sea were numbered. In 1475 Kaffa was taken by the Turks, and the whole peninsula fell under Turco-Tataric dominion.