The influential figure behind the establishment of the Ottoman Empire was Osman I, who reigned from around 1299 to 1326. Osman is regarded as the founder of the empire, which began in northwestern Anatolia and expanded across three continents over the centuries. His leadership set the foundations for a state characterized by military prowess, administrative efficiency, and cultural syncretism. The empire's structure evolved under his successors, particularly his grandson, Orhan, but the legacy of Osman I established the dynastic rule that defined the Ottoman era. His name is also the source of the term "Ottoman," reflecting his central role in the empire's genesis.