I just finished listening to this and it was absolutely fantastic. It also provided me with the most convincing and compelling explanations for the fall of the Western Roman Empire that I have heard. I honestly havent read too much on the Roman Empire so the explanation might be well known, but it wasnt well known to me.
The argument is that the fall of the Western Roman Empire was due to population decline that started around the 2nd century AD due to temperature change that impacted crops and new diseases. The evidence for this is archaeological as well as in documents. There is a clear pattern of degradation of cities starting from that point and Roman laws and proclumations becoming increasingly obsessive over not having enough people on the farms and in the cities. The constant fighting and civil wars also likely helped the spread of disease and increased the death toll. And this loss of population is not an insigificant amount. We are talking about numbers in the 10s of millions of people.
This started a cascading effect that destroyed the Western Roman Empire. Roman taxes were based on land, and with millions of less people taxes were greatly reduced. This caused economic hardship and was probably one of the reasons why Emperors started debasing their currency, which really fucked over their economy. Another consequence was that it resulted in the depopulation of cities, which was the heart of Roman culture and political control. Europe was becoming a less Urban society starting from the 2nd century, not the 5th.
Therefore, Rome was simply not able to defend itself against the barbarian invasions because of they had significantly less people and a shit economy. Rome obviously made that worse by having such a unstable political system and conastat civil wars.
Another key factor is that the barbarians did not invade Rome to rape and pillage and destroy. They actually wanted to settle there and greatly admired Roman culture. This can be seen in the Visagoth Spain, Lombard Italy, and Frankish Gaul. They retained Roman institutions and culture. The main issue, was that there simply wasnt the population and economy now to support an urban population, which was the basis for Roman society. A population decline that started well before the fall of the Roman Empire.
Therefore, we shouldnt see this as oh those great and illustrious Romans and the evil barbarians, and bemone the fall of Civilization due to avoidable forces, but a decline in urban culture due to disease and population decline. Culture still exists, it just became more and more localized and rural. And personally, I'd take manorial serfdom over slavery any day.
Why the, did the West fall and not the East? Well, the speaker makes a very good point that it is simply geography, population and wealth. The West simply had a lot more border to defend than the East. They also were much poorer and had less population. This situation was exacerbated by the reforms of Diocletian who split the empire. Well, the west could no longer rely on the population and the wealth of the East. Simply put, the East survived because it could better defend against invasions and was better able to cope with the depopulation forces that were weakening the West.
The speaker suggests, then, that we should see the periods from 2nd-7th century AD as a decline in urban culture and economy for Europe. It was only until the 8th century that Europe started to recover, thanks to Viking and Islamic trade networks that stimulated European economy, feudalism and manorial agriculture that improved productivity and simply a general uptick in population.