straining the Eastern Empire militarily. Following these wars, Rome and other Italian cities would fall into severe decline (Rome itself was almost completely abandoned). Another blow came with the Persian invasion of the East in the 7th century, immediately followed by the Muslim conquests, especially of Egypt, which curtailed much of the key trade in the Mediterranean on which Europe depended. The Empire was to live on in the East for many centuries, and enjoy periods of recovery and cultural brilliance, but its size would remain a fraction of what it had been in classical times. It became an essentially regional power, centered on Greece and Anatolia. Modern historians tend to prefer the term Byzantine Empire for the eastern, medieval stage of the Roman Empire. Highlights The decline of the Western Roman Empire was a process spanning many centuries; there is no consensus when it might have begun but many dates and time lines have been proposed by historians. 3rd century The Crisis of the Third Century (234–284), a period of political instability. The reign of Emperor Diocletian (284–305), who attempted substantial political and economic reforms, many of which would remain in force in the following centuries. 4th century The reign of Constantine I (306–337), who built the new eastern capital of Constantinople and converted to Christianity, legalizing and even favoring to some extent this religion. All Roman emperors after Constantine, except for Julian, would be Christians. The first war with the Visigoths (376–382), culminating in the Battle of Adrianople (August 9, 378), in which a large Roman army was defeated by the Visigoths, and Emperor Valens was killed. The Visigoths, fleeing a migration of the Huns, had been allowed to settle within the borders of the Empire by Valens, but were mistreated by the local Roman administrators, and rebelled. The reign of Theodosius I (379–395), last emperor to reunite under his authority the western and eastern halves of the Empire. Theodosius continued and intensified the policies against paganism of his predecessors, eventually outlawing it, and making Nicaean Christianity the state religion. 5th century The Crossing of the Rhine: on December 31, 406 (or 405, according to some historians), a mixed band of Vandals, Suebi and Alans crossed the frozen river Rhine at Moguntiacum (modern Mainz), and began to ravage Gaul. Some moved on to the regions of Hispania and Africa. The Empire would never regain control over most of