Which Ottoman sultan founded the empire around 1299?

Osman I is traditionally regarded as the founder of the Ottoman Empire, which emerged around 1299.

Osman was a frontier ruler, or bey, in northwestern Anatolia during the late 13th and early 14th centuries. His small principality was based near Söğüt and bordered the weakening Byzantine Empire, giving his followers opportunities for raids, alliances and territorial expansion.

The date 1299 is a traditional marker rather than a precisely documented founding ceremony. The Ottoman state developed gradually from a frontier beylik, and later rulers expanded it into a major empire. Osman’s son Orhan captured Bursa in 1326 and made it an important Ottoman capital, while later sultans transformed the principality into a regional power.

A common mix-up is crediting Orhan with founding the empire because he established its early institutions and expanded its territory significantly. Osman, however, gave his name to the dynasty and is the standard answer to questions about the empire’s founder.