Rumelia

Murad I (1326-1389) ruled the Ottoman state for some twenty-seven years, moving its capital to Edirne in Europe, reducing the Balkan principalities to vassalage, and developing the institutions of Ottoman government. He was killed at the Battle of Kosovo in 1389.

Orhan Ghazi (c. 1281-1362) took Bursa, Nicaea and Nicomedia from the Byzantines, made Bursa his capital, and carried the Ottomans across the Dardanelles into Europe. Under him the frontier principality acquired the coinage, institutions and territory of a state.