What is bothering Professor Bryan Ward-Perkins in his excellent book "The Fall of Rome: And the End of Civilization" (2006)? The introduction to chapter 5 gives a clue.
"It is currently deeply unfashionable to state that anything like a 'crisis' or a 'decline' occurred at the end of the Roman empire, let alone that a 'civilization' collapsed and a 'dark age' ensued. The new orthodoxy is that the Roman world, in both East and West, was slowly, and essentially painlessly, 'transformed' into a medieval form.So, Professor, what was it really like?
However, there is an insuperable problem with this new view: it does not fit the mass of archaeological evidence now available, which shows a startling decline in western standards of living during the fifth to seventh centuries! This was a change that affected everyone, from peasants to kings, even the bodies of saints resting in their churches.
It was no mere transformation—it was decline on a scale that can reasonably be described as 'the end of a civilization'. "
"Some of the recent literature on the Germanic settlements reads like an account of a tea party at the Roman vicarage. A shy newcomer to the village, who is a useful prospect for the cricket team, is invited in. There is a brief moment of awkwardness, while the host finds an empty chair and pours a fresh cup of tea; but the conversation, and village life, soon flow on. The accommodation that was reached between invaders and invaded in the fifth- and sixth-century West was very much more difficult, and more interesting, than this.Razib Khan's post here recommended this.
The new arrival had not been invited, and he brought with him a large family; they ignored the bread and butter, and headed straight for the cake stand. Invader and invaded did eventually settle down together, and did adjust to each other's ways — but the process of mutual accommodation was painful for the natives, was to take a very long time, and, as we shall see in Part Two, left the vicarage in very poor shape. "