Ottoman Ayan
The Ottoman ayan (singlular: ayn) were local notables or dynasts that maintained different extents of administrative control over swaths of land in the Ottoman Empire from the 16th to the early 19th centuries. These dynasts held significant autonomy from the central Ottoman government but did not challenge the state. Though the title could only be earned by Muslims, their leadership was secular. This elite class consisted of, “Wealthy merchants, heads of Janissary garrisons, leaders of important craft guilds, those who had bought the right to collect taxes for the government in Istanbul, and those who supervised the distributions of wealth generated by, and the maintenance of, pious endowments.” Ultimately, their presence was a part of a greater decentralizing trend experienced in the Ottoman Empire beginning in the 16th century, one which would come to define the Empire’s structure until its fall in the early 20th century.
Ottoman Empire
In the century after the death of Osman I, Ottoman rule began to extend over Anatolia and the Balkans. Osman's son, Orhan, captured the northwestern Anatolian city of Bursa in 1326, making it the new capital of the Ottoman state and supplanting Byzantine control in the region. The important port city of Thessaloniki was captured from the Venetians in 1387 and sacked. The Ottoman victory at Kosovo in 1389 effectively marked the end of Serbian power in the region, paving the way for Ottoman expansion into Europe. The Battle of Nicopolis in 1396, widely regarded as the last large-scale crusade of the Middle Ages, failed to stop the advance of the victorious Ottoman Turks.