Reasons for the Collapse of State-Level Societies

Collapse, in the context of civilizations, is the “significant loss of an established level of sociopolitical complexity.” But what causes societies to collapse?

Sociopolitical complexity manifests itself in various ways:

• Centralization of power: a central administration with bureaucracy, taxation, foreign trade, diplomacy, shared ideology, institutionalized religion, investment in monumental architecture (e.g. palaces, statues, monuments), and urbanization
• Geographic expansion through conquest or economic dominance
• Specialization of labour and social stratification
• Cultural reach beyond geographic borders
• Domestication of plant/animal species
• Science and technology
• Arts and crafts

Any significant drop in several or all of these is indicative of societal collapse. The clearest evidence in the archaeological record is generally a pronounced reduction in population size and density. Collapse, or perhaps more aptly decline, tends to have multiple causes and is rarely abrupt.

According to Diamond, there are five common reasons for societal collapse: environmental damage, climate change, cessation of long-distance trade for critical resources, warfare, and maladaptive responses to the preceding four factors. Plenty of researchers have questioned which members of the quintet were really behind various collapses in history. Instead of looking at individual cases, we can analyse publicly available data to understand why societies generally disappear.

Mortality of states

Recently, Scheffer et al. (2023) created a data set on the mortality of states (MOROS), which covers 5,000 years of civilizations, or more accurately, state-level societies. Their main goal was to come up with the longevity or mortality of states: what is the age at which societies typically vanish?

While the data set is riddled with typographical errors, contains gaps in key fields, and lacks documentation, it can be used to show the most common reasons for societal collapse. All code used to generate the insights in this post is available on GitHub. You can re-run the Jupyter notebook directly in the browser thanks to Zoose for GitHub Codespace.

Longevity

While MOROS comprises state-level societies over the past five millennia, Seshat holds more than 15,000 years of all kinds of societies. Seshat lacks reasons for collapse or geographical regions though.

The mean longevity of societies based on Seshat is 326 years with a mode of 163 years. The mode is calculated from a kernel density estimate of the histogram.

MOROS sports a mean longevity of state-level societies of 228 years. On average, we count 111 years from the peak of a society until its ultimate demise. The mode is 120 years. The authors do not mention how to obtain comparable figures from the raw MOROS data set available, neither in the article nor in the supplementary materials. I have reverse-engineered these from the published charts by filtering state-level societies that have no causes for collapse listed at all.

Based on these findings, we conclude that the average society collapses only 228–326 years after its formation. That said, the political system does matter:

Both states and kingdoms last longer than the average state-level society. Nation states fare the worst.

Longevity by region

What the authors do not investigate is the longevity of state-level societies by region. There are marked differences in the longevity by region.

If we exclude regions with few state-level societies, it becomes clear that societies in Europe last longer than in Africa or Asia. That difference is almost half a century.

Region	Mean longevity	Median longevity	Entries
South America	367	421	6
North America	332	284	4
Europe	257	230	58
Africa	240	200	61
Asia	209	166	163
Oceania	38	38	2

Timeline of societal collapses

When did state-level societies collapse in the last 5,000 years?

Causes for collapse

Let’s get back to the original question: What causes state-level societies to collapse? The main causes are shown in the figure below.

Rather unsurprisingly, military conquest is at the top. Nothing ends a central administration better than a foreign army rolling into the capital and taking over. The second most common reason for societal collapses is not a single cause but rather a combination of several. Such multi-causal collapses are sometimes referred to as systems collapses, in which a single or few smaller failures cascade through a society and cause a complete breakdown. We shall return to multi-causal collapses in a bit.

What is also obvious is that climate change by itself is rarely the cause for a civilization to cease, although it is known to have been a crucial factor in the Late Bronze Age collapse in the Eastern Mediterranean, which I recently explored in an essay for an archaeology course at the University of Oxford. This event corresponds to the tiny bump around 1200 BCE in the aforementioned timeline.

Even when there is not a single cause for the collapse of a state-level society, conquest is still the most common factor. Disintegration of society, civil wars, internal rebellions, cessation of trade relations, governmental transitions, climate change, economic problems, revolutions, and epidemics are also featured prominently.

Natural causes, such as earthquakes, floods, wildfires, and volcanic eruptions rarely end civilizations, as societies tend to be fairly resilient against nature’s force.

Which causes co-occur the most?

Earthquakes, environmental collapse (i.e. ecological overshoot or resource depletion), inequality, and climate change are commonly found in the same mix. Likewise, famine, migration, revolution, and epidemics. This makes perfect sense: famine may force people to seek their luck elsewhere. Alternatively, famine can lead to malnourishment and epidemics, which are the breeding ground for uprisings. Political mismanagement, rebellion, revolution, and inequality are also best buddies, which is hardly surprising: corrupt elites exacerbate inequality, which may enrage the masses to rebel against their overlords. That often ends with a revolution.

The heat map also demonstrates that rebellion/revolution are rarely found in the same collapse as transition/disintegration. Disintegration is a slow decline that often leaves a power vacuum, whereas transitions of power do not. Rebellions and revolutions are swift and often violent.