Overview of historiography
Historiographically, the primary issue historians have looked at when analyzing any theory is the continued existence of the Eastern Empire or Byzantine Empire, which lasted almost a thousand years after the fall of the West. For example, Gibbon implicates Christianity in the fall of the Western Empire, yet the eastern half of the Empire, which was even more Christian than the west in geographic extent, fervor, penetration and vast numbers continued on for a thousand years afterwards (although Gibbon did not consider the Eastern Empire to be much of a success). As another example, environmental or weather changes affected the east as much as the west, yet the east did not "fall."
Theories will sometimes reflect the particular concerns that historians might have on cultural, political, or economic trends in their own times. Gibbon's criticism of Christianity reflects the values of the Enlightenment; his ideas on the decline in martial vigor could have been interpreted by some as a warning to the growing British Empire. In the 19th century socialist and anti-socialist theorists tended to blame decadence and other political problems. More recently, environmental concerns have become popular, with deforestation and soil erosion proposed as major factors, and destabilizing population decreases due to epidemics such as early cases of bubonic plague and malaria also cited. Global climate changes of 535–536, perhaps caused by the possible eruption of Krakatoa in 535, as mentioned by David Keys and others, is another example. Ideas about transformation with no distinct fall mirror the rise of the postmodern tradition, which rejects periodization concepts (see metanarrative). What is not new are attempts to diagnose Rome's particular problems, with Satire X, written by Juvenal in the early 2nd century at the height of Roman power, criticizing the peoples' obsession with "bread and circuses" and rulers seeking only to gratify these obsessions.
One of the primary reasons for the vast number of theories is the notable lack of surviving evidence from the 4th and 5th centuries. For example, there are so few records of an economic nature it is difficult to arrive at even a generalization of the economic conditions. Thus, historians must quickly depart from available evidence and comment based on how things ought to have worked, or based on evidence from previous and later periods, on inductive reasoning. As in any field where available evidence is sparse, the historian's ability to imagine the 4th and 5th centuries will play as important a part in shaping our understanding as the available evidence, and thus be open for endless interpretation.
The end of the Western Roman Empire traditionally has been seen by historians to mark the end of the Ancient Era and beginning of the Middle Ages. More recent schools of history, such as Late Antiquity, offer a more nuanced view from the traditional historical narrative.
There is no consensus on a date for the start of the Decline. Gibbon started his account in 98.Goths and other Barbarians into the Balkan provinces, and the situation of the Western Empire generally worsened thereafter, with recoveries being incomplete and temporary. Significant events include the Battle of Adrianople in 378, the death of Theodosius I in 395 (the last time the Roman Empire was politically unified), the crossing of the Rhine in 406 by Germanic tribes, the execution of Stilicho in 408, the sack of Rome in 410, the death of Constantius III in 421, the death of Aetius in 454, and the second sack of Rome in 455, with the death of Majorian in 461 marking the end of the last opportunity for recovery.
The year 376 is taken as pivotal by many modern historians. In that year there was an unmanageable influx of
Gibbon took September 4, 476 as a convenient marker for the final dissolution of the Western Roman Empire, when Romulus Augustus, the last Emperor of the Western Roman Empire, was deposed by Odoacer, a Germanic chieftain. Some modern historians question the significance of the year 476 for its end. Julius Nepos, the Western emperor recognized by the Eastern Roman Empire, continued to rule in Dalmatia, until he was assassinated in 480. The Ostrogothic rulers of Italia considered themselves upholders of the direct line of Roman tradition, and the Eastern emperors considered themselves the sole rightful Roman rulers of a united empire. Roman cultural traditions continued throughout the territory of the Western Empire, and a recent school of interpretation argues that the great political changes can more accurately be described as a complex cultural transformation, rather than a fall.