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by Florian Ulrich Jehn

Why do civilizations collapse? For some civilizational collapses in the past there is one striking event that leads to a quick end, like environmental damage for the people on the Easter Islands. For other civilizations, several causes interact with each other, as it happened for the Maya, where environmental damage, climate change and hostile neighbors sealed their fate (Diamond, 2011). But the most mysterious case I came across is the simultaneous collapse of almost all major empires in the Mediterreanen during the late Bronze Age. In only around 50 years between 1200 and 1150 BCE the Mycenaean Kingdoms and the Hittite Empire dissolved, Egypt lost its control over the Levante and broke down shortly after. Only Elam and the Assyrian Empire survived somewhat intact. To put this into perspective, there weren’t many states around in this time of human history. Depending on how you count it this means that most existing states on Earth in this time either collapsed or declined. There is less data about China and India for the late Bronze Age, but there are some indications that they also struggled at a similar time, which would make this a global crisis that involved every state that existed at that time. However, as the data from India and China is very scarce I will focus on the Mediterranean, describe my current understanding of the Bronze Age collapse and what we might be able to learn from it today. 

So, what happened? This is still debated much and there are many conflicting theories, but I try to tell here the story that seems most likely to me (I am not a historian, so maybe take this with a grain of salt). I’ve seen many papers that traced the collapse back to only one or a few causes, but it made more sense to me that basically all proposed causes are responsible to some degree and I try to highlight their connections in the text and Figure 2. 

We know from the archaeological record that most of the cities in the region were destroyed by force (Figure 1). The people who destroyed those cities are usually simply called “Sea People”. They have this vague name because they do not consist of a single culture. Depending on the location and year their composition varied considerably (Burlingame, 2011). Also, they do not seem to have any overarching command structure and attacks happen more or less randomly. From the movement of their attacks we can see that the general direction the sea people moved was from north to south and it seems that along the way they either destroyed the local population or integrated them into their move southwards (Carlin, 2019). 

Other research links these movements to a drought that led to widespread famines (Weiss, 1982), which was likely caused by a cooling of the mediterranean sea (Drake, 2012). This decreased evaporation, which led to reduced precipitation, resulted in a drought and famine. The sea itself cooled because of a large volcanic eruption of Mount Hekla in Iceland (Yurko, 1999), that likely produced a volcanic autumn that reduced temperature globally and clouded the sky (this is also the link to the problems of the civilizations in India and China). 

Figure 1:  Map of the Sea People invasions in the Aegean Sea and Eastern Mediterranean at the end of the Late Bronze Age (blue arrows). Some of the major cities impacted by the raids are denoted with historical dates. Inland invasions are represented by purple arrows. (Source: Kaniewski et al., 2011) 

But this climatic approach does not explain everything. The civilizations in this part of earth already survived similar events in the past. For example the destruction of the Minoan civilization on Crete (which is in the middle of the eastern Mediterranean) was caused by another major volcanic eruption (Marinatos, 1939). However, all other civilizations survived mostly unharmed. This indicates that also the societal structure comes into play. There are indications that the civilizations of that time were highly centralized, with the main cities and palaces collecting all of the output of the surrounding farms and workshops (Nakassis et al., 2011). The resources collected in this way were then used to trade and to satisfy key supporters of the ruling class. However, this system relies on the ability of the central government to collect the output of everyone else. This ability was disrupted by the changing climate. The cities in the Mediterranean usually had a higher need for food and other resources to maintain themselves than their immediate surroundings were able to deliver. Thus, they relied on the smaller cities to regularly provide them with food. With the changing climate, the smaller cities needed the food they produced for themselves and stopped their deliveries to the main cities (Knitter et al., 2019). Without those deliveries the central authority had two problems at once. Suddenly there is a shortage of daily everyday goods the citizens needed but, they also missed out on valuable trade goods. Those trade goods were quite important, as the states of that times were connected in a vast trade network reaching from Egypt to Scandinavia (Varberg et al., 2020). This trade network was essential, as all states of that time needed tin and copper to produce bronze. While copper is relatively abundant and can be mined in many places, large tin deposits are much rarer.   Major deposits can be found in present day Spain, Southwest England and Afghanistan (Berger et al., 2019). Therefore, without trade you lose the access to tin, which means you cannot smelt bronze anymore. As bronze was especially important for the production of weapons and armor, a loss of it means a reduced ability to defend yourself against invaders. Another important function of the trade network was to keep in connection with the other empires. There are several indications that the empires helped each other out with food and military aid during emergencies (Burlingame, 2011). What also made defense much harder was a series of earthquakes that hit the Mediterranean at that time. They likely destroyed much of the fortifications and palaces in the region, which left the cities defenseless and in chaos (Nur and Cline, 2000). All those factors were further enhanced by the impact of diseases. There are several indications that a kind of pandemic was rampant during this time as well. However, it is unclear which diseases it was. Likely candidates include the bubonic plague and smallpox (Norrie, 2016). This destabilized society and decreased the available resources, which led to migration and finally to pressure on other cities. The final contributing factor I found is civil war. There are several cities where only the palace is burned down, while the rest of the city remained unharmed, which is an indication of a violent uprising (Carlin, 2019). 

All those factors draw a very complicated picture of the Bronze Age collapse (Figure 2). There is not a single defining cause for the collapse. Every factor on its own would likely not have been enough to topple several Bronze Age empires. However, their interaction led to a quick end of the Bronze Age, which had been relatively stable for centuries or even millennia. 

Figure 2: Interaction of the different factors that led to the late Bronze Age collapse (own figure). 

The reason I am trying to tell this story is that it reminds me of the current situation of the world. There are many factors contributing to a complex system of which we don't always have a deep understanding or overview of. It is really hard to pinpoint the date when it is too late for a system before it collapses. When was the point the fate of the people of the Bronze Age was sealed? When Mount Hekla erupted? When the centralized structure collapsed? When tin became unavailable? The causes that seem most likely to me is the eruption of Mount Hekla and the series of earthquakes.Those two events started a kind of chain reaction by interacting with the way the society of that time was organised. A volcanic eruption that hit a different kind of society would not have been so fatal, as was shown by the earlier eruption at Crete. However, it is almost impossible to pinpoint the main cause of or even determine if there is something like this. This highlights how difficult it is to really find the exact tipping point of a system. 

There is also some research that shows that humans have difficulties finding tipping points and that we might even be lacking the right techniques to do this right (Dudney and Suding, 2020). Therefore, I think we should be more careful when it comes to tipping points in our modern world. Right now this seems most urgent for climate change. We have a lot of tipping points in our climate system like thawing permafrost or a quickly dying rainforest (Lenton et al., 2019). And even though we are getting to understand those better, there are still many unknowns. We can learn from the Bronze Age collapse that a civilization can shine its brightest shortly before its destruction (Carlin, 2019). And in many respects the civilization of that time was not that different to the one we have today, like the vast trade networks, the interdependence of states and the need to acquire certain scarce resources. However, we also have more resources and more knowledge than the people in the Bronze Age. Also, we are much more connected and better equipped to help  each other out. Still, we should not be too self assured, as the people of the Bronze Age might also have thought that they had it all figured out, right before disaster struck. 

Imagine a person that was born 1230 BC in Ugarit, a prosperous city of the vast Hittite Empire. Everything seems to be going well. The cisterns and granaries are full, goods and people from all over the known world regularly arrive at the city and a surprisingly large portion of the population is able to write. Now fast forward 80 years to 1150 BC. Ugarit is a blackened ruin, the Hittite Empire simply does not exist anymore, everyone she knew is dead from disease, war and famine and the sun has not shown through the grey clouds for years. 

I hope we can avoid such a fate for our current civilization. 



Thanks to Jan Wittenbecher, Peter Ruschhaupt, Lutz Breuer, Matteo Trevisan and Luise Wolf for proofreading this text and providing valuable comments!

If you want to learn more about the topic you can find all the resources I used below. Also, there is a somewhat similar post from earlier this year



Berger, D., Soles, J. S., Giumlia-Mair, A. R., Brügmann, G., Galili, E., Lockhoff, N. and Pernicka, E.: Isotope systematics and chemical composition of tin ingots from Mochlos (Crete) and other Late Bronze Age sites in the eastern Mediterranean Sea: An ultimate key to tin provenance?, edited by A. Zerboni, PLoS ONE, 14(6), e0218326, doi:10.1371/journal.pone.0218326, 2019.

Burlingame, K.: Forces of Destruction: The Collapse of the Mediterranean Bronze Age, Bachelor Thesis, Pennsylvania State University., 2011.

Carlin, D.: Chapter 3: The End of the World as They Knew It, in The end is always near: apocalyptic moments, from the Bronze Age collapse to nuclear near misses, HarperCollins Publishers, New York, NY., 2019.

Diamond, J. M.: in Collapse: how societies choose to fail or survive, Penguin Books, New York, NY., 2011.

Drake, B. L.: The influence of climatic change on the Late Bronze Age Collapse and the Greek Dark Ages, Journal of Archaeological Science, 39(6), 1862–1870, doi:10.1016/j.jas.2012.01.029, 2012.

Dudney, J. and Suding, K. N.: The elusive search for tipping points, Nat Ecol Evol, doi:10.1038/s41559-020-1273-8, 2020.

Kaniewski, D., Van Campo, E., Van Lerberghe, K., Boiy, T., Vansteenhuyse, K., Jans, G., Nys, K., Weiss, H., Morhange, C., Otto, T. and Bretschneider, J.: The Sea Peoples, from Cuneiform Tablets to Carbon Dating, edited by K. Hardy, PLoS ONE, 6(6), e20232, doi:10.1371/journal.pone.0020232, 2011.

Knitter, D., Günther, G., Hamer, W. B., Keßler, T., Seguin, J., Unkel, I., Weiberg, E., Duttmann, R. and Nakoinz, O.: Land use patterns and climate change—a modeled scenario of the Late Bronze Age in Southern Greece, Environ. Res. Lett., 14(12), 125003, doi:10.1088/1748-9326/ab5126, 2019.

Lenton, T. M., Rockström, J., Gaffney, O., Rahmstorf, S., Richardson, K., Steffen, W. and Schellnhuber, H. J.: Climate tipping points — too risky to bet against, Nature, 575(7784), 592–595, doi:10.1038/d41586-019-03595-0, 2019.

Marinatos, S.: The Volcanic Destruction of Minoan Crete, Antiquity, 13(52), 425–439, doi:10.1017/S0003598X00028088, 1939.

Nakassis, D., Parkinson, W. A. and Galaty, M. L.: Redistribution in Aegean Palatial Societies Redistributive Economies from a Theoretical and Cross-Cultural Perspective, American Journal of Archaeology, 115(2), 177–184, doi:10.3764/aja.115.2.177, 2011.

Norrie, P.: How Disease Affected the End of the Bronze Age, in A History of Disease in Ancient Times: More Lethal than War, edited by P. Norrie, pp. 61–101, Springer International Publishing, Cham., 2016.

Nur, A. and Cline, E. H.: Poseidon’s Horses: Plate Tectonics and Earthquake Storms in the Late Bronze Age Aegean and Eastern Mediterranean, Journal of Archaeological Science, 27(1), 43–63, doi:10.1006/jasc.1999.0431, 2000.

Varberg, J., Kaul, F. and Gratuze, B.: Bronze Age Glass and Amber Evidence of Bronze Age long distance exchange, Adoranten, (2019), 5–29, 2020.

Weiss, H.: The decline of Late Bronze Age civilization as a possible response to climatic change, Climatic Change, 4(2), 173–198, 1982.

Yurko, F. J.: End of the Late Bronze Age and other crisis periods: a volcanic cause?, in Gold of praise: studies on ancient Egypt in honor of Edward F. Wente, edited by E. F. Wente, E. Teeter, and J. A. Larson, Oriental Institute of the University of Chicago, Chicago, Ill., 1999.





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The Late Bronze Age collapse is an interesting case I'd love to see more work on. Thanks a lot for posting this.

I once spent 1h looking into this as part of a literature review training exercise. Like you, I got the impression that there likely was a complex set of interacting causes rather than a single one. I also got the sense, perhaps even more so than you, that the scope, coherence, dating, and causes are somewhat controversial and uncertain. In particular, I got the impression that it's not clear whether the eruption of the Hekla volcano played a causal role since some (but not all) papers estimate it occurred after the collapse.

I'll paste my notes below, but obviously take them with a huge grain of salt given that I spent only 1h looking into this and had no prior familiarity with the topic.

Late Bronze Age collapse, also known as 3.2 ka event


  • Eastern Mediterranean
  • Quick: 50 years, 1200-1150 BCE
  • Causes: “Several factors probably played a part, including climatic changes (such as those caused by volcanic eruptions), invasions by groups such as the Sea Peoples, the effects of the spread of iron-based metallurgy, developments in military weapons and tactics, and a variety of failures of political, social and economic systems.”

In a recent paper, Knapp & Manning (2016) conclude the collapse had several causes and more research is needed to fully understand them:

“There is no final solution: the human-induced Late Bronze Age ‘collapse’ presents multiple material, social, and cultural realities that demand continuing, and collaborative, archaeological, historical, and scientific attention and interpretation.”

“Among them all, we should not expect to find any agreed-upon, overarching explanation that could account for all the changes within and beyond the eastern Mediterranean, some of which occurred at different times over nearly a century and a half, from the mid to late 13th throughout the 12th centuries B.C.E. The ambiguity of all the relevant but highly complex evidence—material, textual, climatic, chronological—and the very different contexts and environments in which events and human actions occurred, make it difficult to sort out what was cause and what was result. Furthermore, we must expect a complicated and multifaceted rather than simple explanatory framework. Even if, for example, the evidence shows that there is (in part) a relevant significant climate trigger, it remains the case that the immediate causes of the destructions are primarily human, and so a range of linking processes must be articulated to form any satisfactory account.”

While I’ll mostly focus on causes, note that also the scope of the collapse and associated societal transformation is at least somewhat controversial. E.g. Small:

“Current opinions on the upheaval in Late Bronze Age Greece state that the change from the Late Bronze Age to the Geometric period 300 years later involved a transformation from a society based upon complex chiefdoms or early states to one based upon less complex forms of social and political structure, often akin to bigman societies. I will argue that such a transformation was improbable and that archaeologists have misinterpreted the accurate nature of this change because their current models of Late Bronze Age culture have missed its real internal structure. Although Greece did witness a population decline and a shift at this time, as well as a loss of some palatial centers, the underlying structure of power lay in small-scale lineages and continued to remain there for at least 400 years.”

By contrast, Dickinson:

“In the first flush of the enthusiasm aroused by the decipherment of the Linear B script as Greek, Wace, wishing to see continuity of development from Mycenaean Greeks to Classical Greeks, attempted to minimize the cultural changes involved in the transition from the period of the Mycenaean palaces to later times (1956, xxxiii-xxxiv). However, it has become abundantly clear from detailed analysis of the Linear B material and the steadily accumulating archaeological evidence that this view cannot be accepted in the form in which he proposed it. There was certainly continuity in many features of material culture, as in the Greek language itself, but the Aegean world of the period following the Collapse was very different from that of the period when Mycenaean civilization was at its height, here termed the Third Palace Period. Further, the differences represent not simply a change but also a significant deterioration in material culture, which was the prelude to the even more limited culture of the early stages of the Iron Age.” (emphases mine)

Causes that have been discussed in the literature

  • Environmental
    • [This PNAS paper argues against climate-based causes, but at first glance seems to be about a slightly later collapse in Northwest Europe.]
    • Hekla volcano eruption, maybe also other volcano eruptions
      • But dating controversial: “dates for the Hekla 3 eruption range from 1021 BCE (±130)[36] to 1135 BCE (±130)[37] and 929 BCE (±34).[38][39]” (Wikipedia)
      • Buckland et al. (1997) appear to argue against volcano-hypotheses, except for a few specific cities
    • Drought
      • Bernard Knapp; Sturt w. Manning (2016). "Crisis in Context: The End of the Late Bronze Age in the Eastern Mediterranean". American Journal of Archaeology. 120: 99
      • Kaniewski et al. (2015) – review of drought-based theories
      • Matthews (2015)
      • Langguth et al. (2014)
      • Weiss, Harvey (June 1982). "The decline of Late Bronze Age civilization as a possible response to climatic change". Climatic Change. 4 (2): 173–198
      • Middleton, Guy D. (September 2012). "Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies". Journal of Archaeological Research. 20 (3): 257–307
    • Earthquakes
    • Epidemics (mentioned by Knapp & Manning)
  • Outside invasion
    • By unidentified ‘Sea Peoples’
    • For Greece: by ‘Dorians’
    • By broader ‘great migrations’ of peoples from Northern and Central Europe into the East Mediterranean
    • Dickinson against invasion theories: “General loss of faith in ‘invasion theories’ as explanations of cultural change, doubts about the value of the Greek legends as sources for Bronze Age history, and closer dating of the sequence of archaeological phases have undermined the credibility of this reconstruction, and other explanations for the collapse have been proposed.”
  • Technology (as a cause for why the chariot-based armies of the Late Bronze Age civilizations became non-competitive)
    • Ironworking
      • Palmer, Leonard R (1962). Mycenaeans and Minoans: Aegean Prehistory in the Light of the Linear B Tablets. New York, Alfred A. Knopf
    • Changes in warfare: large infantry armies with new (bronze) weapons
      • Drews, R. (1993). The End of the Bronze Age: Changes in Warfare and the Catastrophe ca. 1200 B.C. (Princeton)
  • Internal problems
    • “political struggles within the dominant polities” (mentioned by Knapp & Manning)
    • “inequalities between centers and peripheries” (mentioned by Knapp & Manning)
  • Synthesis: general systems collapse a la Tainter

Types of evidence

  • “material, textual, climatic, chronological” (Knapp & Manning 2016)
    • Textual evidence very scarce (Robbins)
    • Archeological evidence inconclusive, can be interpreted in different ways (Robbins)

Thank you for your notes. Really quite interesting. I was not aware that the dating of the Hekla eruption was so disputed. The reason I focussed on it was that droughts seemed to me like they played a crucial role. The research by Drake et al. argued (relying on isotope data) that this drought was caused by a cooling of the sea, which in turn needs an explanation. And the most likely explanation seemed to be a volcanic eruption.

But I agree that it is overall very hard to understand the timing of all those events. Especially as it played out differently in different parts of the region. In some regions maybe the pandemic struck first, while it was migration or drought in others. I had hoped to highlight  this complex web in my second figure. 

Thanks! Interesting to hear what kind of evidence we have that points toward droughts and volcanic eruptions.

Note that overall I'm very uncertain how much to discount the Hekla eruption as a key cause based on the uncertain dating. This is literally just based on one sentence in a Wikipedia article, and I didn't consult any of the references. It certainly seems conceivable to me that we could have sufficiently many and strong other sources of evidence that point to a volcanic eruption that we overall should have very high credence that the eruption of Hekla or another volcano was a crucial cause.

Guys, great post and discussion. I was taking a look at the discussion about Hekla's role... even if the eruption succeeded the breakdown of those civilizations by half a century, it'd likely have an effect concerning their prospects for recovery.

Wow, vulcano erupting, a famine, an earthquake, a  pandemic, civil wars and rioting sea people, that's quite a task. Really interesting read, thanks for writing it! And the graph ended up really nicely. 

But this climatic approach does not explain everything. The civilizations in this part of earth already survived similar events in the past. For example the destruction of the Minoan civilization on Crete (which is in the middle of the eastern Mediterranean) was caused by another major volcanic eruption (Marinatos, 1939). However, all other civilizations survived mostly unharmed. This indicates that also the societal structure comes into play.

This argument didn't seem super watertight to me. There seems to be a lot of randomness involved, and causal factors at play that are unrelated to societal structure, no? For example maybe the other eruption was a little bit weaker, or the year before yielded enough food to store? Or maybe the wind was stronger in that year or something? Would be interesting to hear why the mono- and/or some of the duo-causal historians disagree with societal structure mattering.

However, we also have more resources and more knowledge than the people in the Bronze Age.

I wondered how much this is an understatement. I have no idea of how people thought back then, only the vague idea that the people that spend the most time trying to make sense of things like this were religious leaders and highly confused about bascially everything?

Lastly, your warnings  of tipping points and the problems around the breakdown of trade reminded me of these arguments from Tyler Cowen, warning that the current trade war between China and the US and the strains from the current pandemic could lead to a sudden breakdown of international trade, too.

Thank you. Yeah when I wrote this down I was a bit shocked myself on how many bad things can happen at the same time. 

You're are right that the argument about the comparison with the other eruption is a bit flaky. The problem is that this is so long ago and most written sources were destroyed. So, we have to rely on climatic reconstructions and those are hard. Therefore, I found accounts that both eruptions were of similar strength, but also some which argued that one of them was stronger than the other.  However, the earlier eruption happened smack in the middle of the Bronze Age empires, while the one during the collapse happened in Iceland. So, I would also be very interested in the opinion of someone about this who spend a career on it. 

To your second argument: I agree that we have vastly more ressources and knowledge now. The problem is that it seems to me that our power to destroy ourselves increased as well and the society seems much more unlikely to recover when a really bad disaster would strike. So, my feeling is that stabilizing and destabilizing factors increased in a similar magnitude. 

Thank you for the article from Cowen. I see this danger as well. Such topics always remind of this article. It is mainly a rant about programmers, but it also touches on the problem that much of our infrastructure will be very difficult to restart once its stopped, because so much of it are just improvised stopgap solutions. 

I could not really fit this neatly in the text, but the destruction of Ugarit was the scene for a grim, yet fascinating bit of history that I do not want to withhold from you. During some archeological excavations clay tablets were found with the following text:

“My father, behold, the enemy’s ships came (here); my cities(?) were burned, and they did evil things in my country. Does not my father know that all my troops and chariots(?) are in the Land of Hatti, and all my ships are in the Land of Lukka?… Thus, the country is abandoned to itself. May my father know it: the seven ships of the enemy that came here inflicted much damage upon us.“

This was a desperate call for help, but we were only able to dig up those clay tablets, because the clay was baked by the city burning down around them and the tablets were buried beneath the rubble of the destroyed city. I think this is a stark reminder of what can happen when civilization collapses.

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