The empire emerged from a beylik, or principality, founded in northwestern Anatolia in 1299 by Turkoman tribal leader Osman I. His successors conquered much of Anatolia and expanded into the Balkans by the mid 14th century, transforming their petty kingdom into a transcontinental empire. The Ottomans ended the Byzantine Empire with the conquest of Constantinople in 1453 by Mehmed II, which marked the Ottomans’ emergence as a major regional power. Under Suleiman the Magnificent (1520–1566), the empire reached the peak of its power, prosperity, and political development. By the start of the 17th century, the Ottomans presided over 32 provinces and numerous vassal states, which over time were either absorbed into the Empire or granted various degrees of autonomy.[l] With its capital at Constantinople (modern-day Istanbul) and control over a significant portion of the Mediterranean Basin, the Ottoman Empire was at the centre of interactions between the Middle East and Europe for six centuries.