Leo III the Isaurian, also known as the Syrian, was the first Byzantine emperor of the Isaurian dynasty from 717 until his death in 741. He put an end to the Twenty Years' Anarchy, a period of great instability in the Byzantine Empire between 695 and 717, marked by the rapid succession of several emperors, along with ending the continual defeats and territorial losses the Byzantines had suffered during the 7th century. He successfully defended the Empire against the invading Umayyads and forbade the veneration of icons.