The Byzantine era properly defined came to an end with the fall of Constantinople to the Ottoman Turks in 1453, but by this time the Byzantine cultural heritage had been widely diffused, carried by the spread of Orthodox Christianity, to Bulgaria, Serbia, Romania and, most importantly, to Russia, which became the centre of the Orthodox world following the Ottoman conquest of the Balkans. Even under Ottoman rule, Byzantine traditions in icon-painting and other small-scale arts survived, especially in the Venetian-ruled Crete and Rhodes, where a "post-Byzantine" style under increasing Western influence survived for a further two centuries, producing artists including El Greco whose training was in the Cretan School which was the most vigorous post-Byzantine school, exporting great numbers of icons to Europe. The willingness of the Cretan School to accept Western influence was atypical; in most of the post-Byzantine world "as an instrument of ethnic cohesiveness, art became assertively conservative during the "Turcocratia"" (period of Ottoman rule).