The Ottomans were strong proponents of Sunni Islam.[17] In the 13th century, the kingdom was only in a small portion of northwest Anatolia but by the 16th century, it expanded to the heartland of the Byzantine Empire and its capital, Constantinople. The height of the Ottoman Empire occurred under the sultans Selim the Grim, also known as Selim I (1512–1520) and Suleyman the Magnificent (1520–1566). Under their reigns, the Turks conquered Egypt, Syria, and the North coast of Africa, the Red Sea, the island of Rhodes, and the Balkans all the way to the Great Hungarian Plain.