THE OTTOMAN DYNASTY created the most enduring empire in human history. The Ottomans originally migrated from Central Asia as nomads and settled in the early 14th century as a military Turkic principality in western Anatolia (present-day Turkey), between the frontier zone of the Seljuk state and the Byzantine Empire. The Ottomans emerged into a dominant Muslim force in Anatolia and the Balkans and became the most powerful Islamic state since the breakup of the Abbasid caliphate in 1258. At its height in the 16th and 17th centuries, the empire was the most powerful in the world. Made up of diverse ethnic and religious groups, including Arabs, Armenians, Greeks, Kurds, and Slavs, the empire stretched from Central Europe in the west to Baghdad (Iraq) in the east, from the Crimean Sea in the north to the Upper Nile in Egypt and the Arabian Peninsula (Saudi Arabia) in the south. Named after the founder and first sultan (ruler) of the dynasty, the Ottomans came into prominence with their gradual invasion of the Byzantine Empire that had occupied parts of Asia Minor and southeastern Europe for nearly a thousand years. With the conquest of the Byzantine capital, Constantinople, in 1453 under the rule of Muhammad II (1451–81), famously known as “Mehmet the Conqueror,” the Ottomans extended their dominance over much of Anatolia and southeastern Europe. Constantinople then became the capital of the Ottoman Empire and was renamed Istanbul. After taking Constantinople, the Ottomans, conquered the Fertile Crescent, North Africa from Egypt up to Morocco, and the Arabian Peninsula, including the Hijaz, seizing control of the holy cities of Mecca and Medina. Under Suleiman the Magnificent (1520–66), they expanded into the Balkans in 1521, capturing Belgrade (Serbia and Montenegro) and even besieging the Habsburg capital of Vienna (Austria), forming the largest and one the most powerful empires of the 16th-century world. After the death of Suleiman the Magnificent in 1566, the Ottoman Sultans, also known by the Persian title of Padeshah, became increasingly dependent on the crops of Janissaries, captured Christian slaves trained into elite soldiers, and the clergy class or the ulama, who gradually gained power at the court. The Janissaries were not only a military organization that protected the sultan, but also a warrior, spiritual fraternity, an association inclined in the mystical dimension of ISLAM that upheld a chivalric code of ethics; they were a powerful elite body in the Ottoman Empire. Although the sultans made the important decisions for the empire, including exercising the power to appoint officials to collect taxes and maintain stability within the empire, the grand mufti, the chief religious cleric, legitimized the authority of the sultan as the ruler of the empire. In contrast to their contemporary Muslim states, the Safavids and the Mughals, the Ottoman Sultans shaped the clerics into a state bureaucracy rather than allowing them to evolve into an independent institution.