The fall of the Roman Empire is traditionally dated to year 476 when the last Western Roman Emperor Romulus Augustulus was deposed by Germanic military leader Odoacer despite the fact that the eastern half of empire - the Byzantine Empire has survived for nearly a millennium. The barbarian invasions undoubtedly contributed to the fall of the Roman Empire but some historians believe that the barbarians merely accelerated its collapse.
The first signs of the decline of the Empire can be traced back to the second half of the 2nd century, while the situation in the empire reached its critical point in 235 when emperor Alexander Severus was murdered and the empire broke up into three competing states. The civil war that lasted until the ascension of Diocletian to the throne in 284 and raids of Germanic peoples in the Roman provinces severely hit the Roman economy, in first place the long-distance trade because traveling and transport were no longer safe.
The economic depression and period of general instability has also resulted in a spiritual crisis which gave rise to Christianity and led to profound changes of the Roman society which became similar to the later medieval society in many aspects. The Roman Empire in late antiquity saw the rise of power and influence of large landholders and loss of both political and economic status of the common people.
The Roman Empire managed to survive the so-called Crisis of the Third Century but it never truly recovered from it and changed dramatically in its character. The administrative division of the Roman Empire into four parts (Tetrarchy) and later into two halves led to permanent division of the empire after the death of emperor Theodosius I in 395. While the Eastern part of the Roman Empire that came to be known as the Byzantine Empire gradually increased its power and prestige, the Western Roman Empire was no longer able to repulse the barbarian invaders.
The Western Roman Emperors tried to "buy off" the invading Germanic peoples by allowing them to settle in the Roman provinces in return for their military aid against more hostile barbarian groups. However, they eventually lost power to barbarian military leaders and the Western Roman Emperors held power formally only after the mid-5th century.
The reasons for the fall of the Roman Empire remain a matter of debate among historians. Several theories have been presented ranging from overexpansion, inflation, loss of civic virtue of the Roman population, "barbarization" of the Roman army, spiritual crisis, collapse of traditional trade networks, barbarian invasions, plague, political instability and some others but the collapse of the Roman Empire was most likely caused by a combination of several factors.
