Collapse is what happens when, over centuries, populations decline, mass migrations occur, ideas are forgotten, languages and religions change, law and institutions decay or vanish and legends are born. Famous examples are the end of the Maya, the fall of the Western Roman Empire and the failure of the Mediterranean Bronze Age. Less famous are the end of the Khmer in Cambodia.

What collapse isn’t is things like the end of the Ottoman, Austro-Hungarian or British Empires. Yes, local wars often resulted from these but there wasn’t a large, long term population or economic decline in most of the areas concerned. These Empires fell, or more correctly ‘fell apart’, but did not collapse.

General view

Collapse is often viewed as part of a natural cycle of boom and bust, or of ‘senescence’, as societies inevitably develop weak constitutional structures, esoteric religious views or other ‘bad habits’. Such views are held by many early and modern writers.

Another traditional view, which is slightly out of fashion but recently championed by Bryan Ward-Perkins, is that civilisation collapse is triggered by sustained invasion of ‘barbarians’.

A third traditional view is that changes in technology lead to changes in social structure and the overthrow of oppressive rulers. However, in my view if this were the case then there would not be major population reductions.

A current mainstream view, as advocated by Jared Diamond and many others, is that civilisation collapse in history is a result of human endeavours overtaxing natural resources. This is similar to Joseph Tainter’s view that collapse is the natural end of a cycle resulting from marginal returns on investment in bigger societies.

Alternatively, collapse is often argued to be triggered by climatic events such as sustained droughts. This is, naturally, a popular view amongst those who study ancient climate.

My current view

Collapse is the result of a fall in population, not the prime cause of it.

Collapse happened in the past only in civilisations which had extensive (?land) borders to uncivilised (barbarian) regions. These barbarian regions contained populations which could be quite mobile or easily displaced, and family and feud were more important than law and institutions. Civilisations therefore required large frontier armies to defend themselves from raiding and plunder.

During population fall, maintenance of the frontiers required a greater proportion of the population to become part of the military in order to maintain the frontier. Most of the remaining population was then forced into increased efficiency of food production to feed the military. This required reorganisation of the countryside and the loss of peasant freedoms which led to unrest and further population loss. Ultimately, retreat was necessary to reduce the length of the frontier, leading to the shrinking or, rarely, disappearance of the area of civilisation.

Population loss occurred by two methods that I can currently see:

  1. due to the diversion of trade routes, usually due to an improvement in transport or materials technology, meaning that people migrated out of the area to areas of greater economic activity.
  2. due to pandemic or epidemic.

Examples of the first category are the collapse of the Maya of central America, the Khmer of southeast Asia and, arguably, the early medieval empires of the Silk Road and the gold states of West Africa. In all three cases changes from portage across peninsulas or land regions to sea transport around those regions left these civilisations without trade connections, causing the wealthy to drift away.

(On the other hand it may be possible for improvements in land transport to make sea routes in their turn redundant). Andrew Sherratt recognised the significance of these effects in his writings.

Examples of the second category are the collapse of the Roman Empire and, possibly, the Eastern Mediterranean Bronze Age. In this case, pandemic can affect the barbarian populations too (although to a lesser extent). However, their mobility leads to periods of migration and barbarian populations end up concentrated close to the frontier, thus leading to the over-requirement of the military by the empire or set of civilised states.

The Great Plague (Black Death) did not result in collapse. Western Europe was distant from any barbarian threat, so the economic effects on the peasantry were of population fall were essentially free-market ones, and increased the need for labour over land.

On the other hand, Eastern Europe was faced with barbarian threat from the east and ?south, and showed all the initial patterns of expanding military and loss of peasant freedoms seen in the late Roman Empire. However, the threat (the barbarian steppe nominally ruled over by Khanates) was relatively weak and in the process of settling itself, so never led to the retreat of civilisation to the west.

I believe that the modern world is probably incapable of suffering from this kind of collapse on any scale, due both to its cheap transport, preventing trade advantage, and the lack of ‘barbarians’.