Isauria, in ancient geography, a district of Asia Minor, bounded by Phrygia, Lycaonia, Cilicia, and Pisidia, containing few towns, and known to the ancients chiefly by the marauding excursions of the Isauri, who dwelt in its mountain fastnesses. The Romans sent an army against them in 78 B. 0. under Servilius, who reduced them to submission and gained the surname of Isauricus. As they continued their depredations, the Romans tried with little success to check them by confining them within a circle of fortresses. In the 3d century the Isaurians and Cilicians united themselves into one nation, and one of their chiefs, Trebellia-nus, assumed the title of Roman emperor (264), but was conquered and put to death. They were formidable to the Byzantine emperors, and two of their race, Zeno (474-'91) and Leo III. (718-'41), rose to the Byzantine throne. The capital of Isauria was Isaura, at the foot of Mt. Taurus, a strong and rich city, whose inhabitants destroyed it and themselves by fire when they could no longer resist the siege of Perdiccas, shortly after the death of Alexander the Great. It was rebuilt, and again destroyed by Servilius.