Rise of the Ottoman Empire
The foundation and rise of the Ottoman Empire is a period of history that started with the emergence of the Ottoman principality in , and ended with the conquest of Constantinople on May 29, 1453. This period witnessed the foundation of a political entity ruled by the Ottoman Dynasty in the northwestern Anatolian region of Bithynia, and its transformation from a small principality on the Byzantine frontier into an empire spanning the Balkans and Anatolia. For this reason, this period in the empire's history has been described as the Proto-Imperial Era. Throughout most of this period, the Ottomans were merely one of many competing states in the region, and relied upon the support of local warlords and vassals to maintain control over their realm. By the middle of the fifteenth century the Ottoman sultans were able to accumulate enough personal power and authority to establish a centralized imperial state, a process which was brought to fruition by Sultan Mehmed II (r. 1451-1481). The conquest of Constantinople in 1453 is seen as the symbolic moment when the emerging Ottoman state shifted from a mere principality into an empire, marking a major turning point in its history.
History of the Ottoman Empire
With the demise of the Seljuk Sultanate of Rum (c. 1300), Anatolia was divided into a patchwork of independent states, the so-called Anatolian Beyliks. By 1300, a weakened Byzantine Empire had lost most of its Anatolian provinces to these Turkish principalities. One of the beyliks was led by Osman I (d. 1323/4), from which the name Ottoman is derived, son of Ertuğrul, around Eskişehir in western Anatolia. In the foundation myth expressed in the story known as "Osman's Dream", the young Osman was inspired to conquest by a prescient vision of empire (according to his dream, the empire is a big tree whose roots spread through three continents and whose branches cover the sky). According to his dream the tree, which was Osman's Empire, issued four rivers from its roots, the Tigris, the Euphrates, the Nile and the Danube. Additionally, the tree shaded four mountain ranges, the Caucasus, the Taurus, the Atlas and the Balkan ranges. During his reign as Sultan, Osman I extended the frontiers of Turkish settlement toward the edge of the Byzantine Empire.