Second, Heather says "the landowning provincial literati now shifted their attention to where the money was ... away from provincial and local politics to the imperial bureaucracies." Having set the scene of an Empire stretched militarily by the Sassanid threat, Heather then suggests, using archaeological evidence, that by 400 the Germanic tribes of Europe had "increased substantially in size and wealth" since the first century. Contact with the Empire had increased their material wealth, and that in turn had led to disparities of wealth sufficient to create ruling and military classes capable of maintaining control over far larger groupings than had previously been possible. The Germans had become more formidable foes. Heather then posits what amounts to a domino theory—namely that pressure on peoples very far away from the Empire could result in sufficient pressure on peoples on the Empire's borders to make them contemplate the risk of full scale immigration to the empire. Thus he links the Gothic invasion of 376 directly to Hunnic movements around the Black Sea in the decade before. In the same way he sees the invasions across the Rhine in 406 as a direct consequence of further Hunnic incursions in Germania; as such he sees the Huns as important in the fall of the Western Empire long before they themselves became a military threat to the Empire. He postulates that the Hunnic expansion caused unprecedented invasions of the Empire in 376 and 405-408 by barbarian groupings who had become significantly more politically and militarily capable than in previous eras. This detached territory and denied revenues to an empire already at maximum stretch due to the Sassanid pressure. He disputes Gibbon's contention that Christianity and moral decay led to the decline. He also rejects the political infighting of the Empire as a reason, considering it was a systemic recurring factor throughout the Empire's history which, while it might have contributed to an inability to respond to the challenges of the 5th century, it cannot be blamed for them. Instead he places the fall of the Western Roman Empire on outside military factors, starting with the Sassanids, and ending with the Germanic invasions under pressure from the Huns. Bryan Ward-Perkins Bryan Ward-Perkins's The Fall of Rome and the End of Civilization (2005) takes a traditional view tempered by modern discoveries, arguing that the empire's demise was caused by a vicious circle of political instability, foreign invasion,