The Ottomans were converts to Islam and decendants of Turkish speaking people from Central Asia.
The word ‘Ottoman’ is an European corruption derived from the name Osman, a Turkish leader whose great success as a “fighter for the faith” attracted warriors to his frontier principality.
His successor, ‘Orhan’ (1326-62) drove the Byzantines out of Asia Minor. By taking Adrianople (edirne) he acquired a European base from which Murad I could enter the Balkans and hre defeat a force of Serbians, Bulgarians, Bosnians and Montenegrins at Kosovo in 1389.
Bayezid I (1389-1402) consolodated the Ottoman hold on Anatolia (present day Turkey) and assumed the title of sultan, proclaiming the transforatioun of his dynasty into rulers of an empire.
He tried to besiege Constantinople twice but was distracted by the raisd of Tamerlane, who crushed him at Ankara in 1402.
Wars of succession ravaged the Ottoman lands for 20 years. The Ottoman power reached its peak under Suleiman (1520-66). He was known to his people as Kanunim ‘Lawgiver’ and to dazzled Euorpeans as ‘the Magnificient’. By seizing Rhodes, he made the Ottomans a major sea power and crushed the Hungarians at Mohacs (1526), whilst he lay seige to Vienna in 1529.
His failure to take Vienna, despite two attempts, showed the difficulties of campaigning far afield, which finally set the bounds of the empire.
Then a shattering naval defeat off the Greek coast of Lepanto in 1571 marked the end of the Ottomans expansion for a century.