It was a vast Turkish state founded in the thirteenth century by the Osmani Turks, Turks who were led by descendants of Osman I (1258–c. 1326). By the middle of the next century, the Ottoman Empire consisted roughly of modern-day Turkey (the terms “Turkey” and “Ottoman Empire” are used interchangeably). The empire was expanded further by conquests during the 1400s, including the conquest of the Byzantine Empire in 1453. At its height, the Byzantine Empire extended over an area that included the Balkan Peninsula (present-day Slovenia, Croatia, Bosnia and Herzegovina, Macedonia, Yugoslavia, Romania, Bulgaria, Albania, Greece, and Turkey), Syria, Egypt, Iraq, the northern coast of Africa, Palestine, and parts of Arabia, Russia, and Hungary. The capital was placed at Constantinople (present-day Istanbul, Turkey). Thus the Turks established a Muslim empire that would remain a formidable force and influence in the region and in Europe for the next three centuries.

During the 1500s and 1600s the Ottoman Empire was the most powerful in the world. It reached its most glorious heights during the reign of Süleyman the Magnificent (1494–1566), who ruled from 1520 to 1566: It was he who added parts of Hungary to the Ottoman territory. He also tried to take Vienna, but failed. He did succeed in strengthening the Ottoman navy, which dominated the Mediterranean Sea. Süley-man was not only an expansionist, but a patron of the arts and a builder. He ordered the construction of mosques (to spread the Islamic religion throughout the empire), bridges, and other public works.

But by the time World War I began in 1914, the Ottoman Empire had been in decline for some 300 years and only consisted of Asia Minor, parts of southwestern Asia, and part of the Balkan Peninsula. As one of the losing Central powers, the Ottoman Empire was dissolved in 1922 by the peace treaties that ended the war.