The Ottoman Empire, also historically known in Western Europe as the Turkish Empire or simply Turkey, was a state that controlled much of Southeast Europe, Western Asia and North Africa between the 14th and early 20th centuries. It was founded at the end of the 13th century in northwestern Anatolia in the town of Söğüt by the Oghuz Turkish tribal leader Osman I. After 1354, the Ottomans crossed into Europe, and with the conquest of the Balkans, the Ottoman beylik was transformed into a transcontinental empire. The Ottomans ended the Byzantine Empire with the 1453 conquest of Constantinople by Mehmed the Conqueror.