For anyone curious about academic studies of historical societal collapses, check out Joseph Tainter [1]
> As described in Tainter's Collapse of Complex Societies, societies become more complex as they try to solve problems. [...] Such complexity requires a substantial "energy" subsidy (meaning the consumption of resources, or other forms of wealth).
> When a society confronts a "problem," such as a shortage of energy, or difficulty in gaining access to it, it tends to create new layers of bureaucracy, infrastructure, or social class to address the challenge. Tainter, who first identifies seventeen examples of rapid collapse of societies, applies his model to three case studies: The Western Roman Empire, the Maya civilization, and the Chaco culture.
> For example, as Roman agricultural output slowly declined and population increased, per-capita energy availability dropped. The Romans "solved" this problem by conquering their neighbours to appropriate their energy surpluses (as metals, grain, slaves, other materials of value). However, as the Empire grew, the cost of maintaining communications, garrisons, civil government, etc. grew with it. Eventually, this cost grew so great that any new challenges such as invasions and crop failures could not be solved by the acquisition of more territory. [...]
> It is often assumed that the collapse of the western Roman Empire was a catastrophe for everyone involved. Tainter points out that it can be seen as a very rational preference of individuals at the time, many of whom were actually better off. Tainter notes that in the west, local populations in many cases greeted the barbarians as liberators.
> As described in Tainter's Collapse of Complex Societies, societies become more complex as they try to solve problems. [...] Such complexity requires a substantial "energy" subsidy (meaning the consumption of resources, or other forms of wealth).
> When a society confronts a "problem," such as a shortage of energy, or difficulty in gaining access to it, it tends to create new layers of bureaucracy, infrastructure, or social class to address the challenge. Tainter, who first identifies seventeen examples of rapid collapse of societies, applies his model to three case studies: The Western Roman Empire, the Maya civilization, and the Chaco culture.
> For example, as Roman agricultural output slowly declined and population increased, per-capita energy availability dropped. The Romans "solved" this problem by conquering their neighbours to appropriate their energy surpluses (as metals, grain, slaves, other materials of value). However, as the Empire grew, the cost of maintaining communications, garrisons, civil government, etc. grew with it. Eventually, this cost grew so great that any new challenges such as invasions and crop failures could not be solved by the acquisition of more territory. [...]
> It is often assumed that the collapse of the western Roman Empire was a catastrophe for everyone involved. Tainter points out that it can be seen as a very rational preference of individuals at the time, many of whom were actually better off. Tainter notes that in the west, local populations in many cases greeted the barbarians as liberators.
[1] https://en.wikipedia.org/wiki/Joseph_Tainter