Byzantine Greek kingdom in Anatolia, the Empire of Trebizond, covering the Black Sea coast of north-eastern Turkey to the border with Georgia, fell in 1461. Ottoman Empire Constantinople fell in 1453, marking the end of the Byzantine Empire. Beginning with the Seljuk invasion in the 11th century, and continuing through the Ottoman years, Anatolia underwent a process of Turkification, its population gradually changing from predominantly Christian and Greek-speaking to predominantly Muslim and Turkish-speaking. A class of moneyed ethnically Greek merchants (they commonly claimed noble Byzantine descent) called Phanariotes emerged in the latter half of the 16th century and went on to exercise great influence in the administration in the Ottoman Empire's Balkan domains in the 18th century. They tended to build their houses in the Phanar quarter of Istanbul in order to be close to the court of the Ecumenical Patriarch of Constantinople, who under the Ottoman millet system was recognized as both the spiritual and secular head (millet-bashi) of all the Orthodox subjects (the Rum Millet, or the "Roman nation") of the Empire, often acting as archontes of the Ecumenical See. For all their cosmopolitanism and often western (sometimes Roman Catholic) education, the Phanariots were aware of their Hellenism; according to Nicholas Mavrocordatos' Philotheou Parerga: "We are a race completely Hellenic". The first Greek millionaire in the Ottoman era was Michael Kantakouzenos Shaytanoglu, who earned 60.000 ducats a year from his control of the fur trade from Russia; he was eventually executed on the Sultan's order. It was the wealth of the extensive Greek merchant class that provided the material basis for the intellectual revival that was the prominent feature of Greek life in the second half of the 18th century and the beginning of the 19th century. Greek merchants endowed libraries and schools; on the eve of the Greek War of Independence the three most important centres of Greek learning, schools-cum-universities, were situated in Chios, Smyrna and Aivali, all three major centres of Greek commerce. The outbreak of the Greek War of Independence in March 1821 was met by mass executions, pogrom-style attacks, the destruction of churches, and looting of Greek properties throughout the Empire. The most severe atrocities occurred in Constantinople, in what became known as the Constantinople Massacre of 1821. The Orthodox Patriarch Gregory V was executed on April 22, 1821 on the orders of the Ottoman Sultan, which caused outrage throughout Europe and resulted in