Open and closed state systems: the geography of regional unification

By Lorenzo

Recurring periods of unification were a notable feature of the history of China; notably the QinHan (221BC-220), SuiTang (589-907), and YuanMingQing (1271-1912) periods of unification. (The Northern Song [959-1126] arguably do not count as a full unification, since they never controlled the northern regions, which was under the control of the Liao dynasty [907-1125].) Indeed, of all the major civilisation centres, China was unified more frequently than any other.

Conversely, Europe was never unified and the Mediterranean basin was unified only once–under the Roman Empire. So, why was China repeatedly unified, while the Roman Empire was a one-off?

Unification propensities

The first thing to note, is that we are looking at different propensities to be unified. There were centuries-long periods of Chinese history when it was not united: nevertheless, compared to other civilisation centres, it showed a relatively high propensity for unification. Conversely, the Mediterranean basin had a low propensity to being unified (it was unified once) and Europe as a whole effectively no propensity to being unified (as it never was).

The size of largest and second largest empires.

Note also that propensity to unification is not the same as any more general propensity to large states or mega empires. The former is about the propensity for a specific region to be ruled by a single state, not mere state size or capacity. (Though, of course, state capacity matters in the sense that the region has to be within the possible ambit of control by a single state, given the level of organisational capacity achieved by states in a particular time period.)

Both historical demographer Peter Turchin (here) and historian T. Greer (here) have posted on the contrast between China and Europe. Both of the them reject what Greer calls the fractured land hypothesis, which Greer describes thus:

… they suggest that China’s political unity and Europe’s perpetual disunity are reflections of the unbroken terrain of the first and the disparate geography of the second. Two prominent examples can be found in Paul Kennedy’s Rise and Fall of the Great Powers: Economic Powers and Military Change, 1500-2000 and Jared Diamond’s Guns, Germs, and Steel: The Fate of Human Society.

Turchin and Greer both argue that the geography of China is more similar to Europe’s than the hypothesis requires.

I completely agree with them, the fractured land hypothesis is not at all a satisfactory explanation of the different propensities to unification. Greer concludes his post with:

A close examination of the geography of East Asia suggests that there is no geographic feature capable of explaining the divergent paths of European powers like Germany, France, and the Netherlands that cannot be found in China. Chinese unity did not come because of its geography. It came in spite of it. 

While completely agreeing with the unsatisfactory nature of the fractured land hypothesis, I completely disagree with Greer’s wider conclusion. China’s geography does explain why it had a relatively high propensity to unification–provided we look at in terms of the interaction between geography and state systems.

State systems: how bounded?

In using the concept of a state system, I am adopting the terminology and definition of historical sociologist Charles Tilly in his seminal Coercion, Capital and European States: AD 990-1992:

States form a system to the extent that they interact with each other regularly, and to the degree that their interaction affects the behaviour of each state (p.162).

To explain varying propensities to unification, we have to examined how open or closed, how bounded, a particular state system is. A state system is completely open if it has no borders without effective states (or power projection by states). The contemporary global state system is completely open, it has no such geographical borders. But we have not always had a global state system: in fact, far from it.

A state system is completely closed if it is bounded on all sides by borders without effective states (or power projection by states). Apart from some early periods of state formation in various regions, this has essentially never been the case. A state system can be relatively closed, however. If, for example, all but one border is without effective states (or power projection by states).

The closed and controllable state systems of China

Which is precisely the situation that China was in for most of its history. Until the C19th, no state projected significant state power across its coasts. With the exception of the relatively brief Tibetan Empire (618-842)*, no state projected significant state power into China across a South-to-West-to-North arc from the Vietnam border to the steppes. For most of its history, the only open border for the projection of state power into China was the steppes border.

The interaction between the people of the plough (the Chinese) and the people of the bow (the pastoralist nomads) has been central to Chinese history. But it has been central to Chinese history precisely because, for the overwhelming majority of Chinese history, it has been the only open border across which external state power was projected into the farming lands of China. And that was most emphatically been a product of the geography of China. That its agrarian heartland is a series of river valleys bordered by coasts, jungles, mountains and deserts across which state power was not seriously projected from outside (with the above noted relatively brief Tibetan exception) and by the steppes, across which it was.

Why does that matter for the propensity to be unified? Because the area that is so bounded was able to be controlled (given the transport and communication technology available) by a single state. So, in a period of disunity, if and when one state gained a military advantage over the others, the geography of China meant that the period it needed to sustain that military advantage to roll up the other states in the bounded state space was relatively short. Short enough to generate China’s relatively high propensity to be unified. And, since there was effectively only one border across which rival state power could be projected, there were considerable economies of scale in military effort to be reaped once unification was achieved.

As we are looking at the interactive dynamics of state systems–that is, their movement through time–both military and administrative technology matter. In particular, what level of resource mobilisation states in the relevant state space have the organisational capacity to do, matters. It may take considerable time before one participant develops the organisational capacity to overwhelm the other states in the relevant state space. Hence centuries of disunity even in the case of China. Since we are looking at varying propensities, while geography remains essentially a fixed constraint, only explanation in terms of dynamics–specifically, state system dynamics, given that we are looking at the propensity for the state system to evolve into a single state–has any chance of explaining the pattern.

The Roman exception

If we look at propensity to unification in terms of characteristics (and the dynamic possibilities and patterns therefrom) of state systems, we can see why Europe had effectively no propensity to unification. Once state formation had spread beyond the Mediterranean littoral, it was never a closed state system in the above sense. There were too many borders across which state power could be (and was) projected into too large an area for establishing and maintaining unified control. Which meant too many directions from which unity could be blocked and (especially) military dominance blocked (as a series of would-be hegemons found).

The centuries earlier Mediterranean world that the Roman Republic confronted was quite different. There were no states beyond the Mediterranean littoral, except in the East. The forests of Europe, the deserts of the Sahara, were either empty of states or too much of a barrier for effective projection of state power. Only eastwards–in particular, the Iranian plateau–were there state(s) able to project state power into the Mediterranean littoral. Which was not enough to block Mediterranean littoral unity if one state had enough of a military advantage for long enough.

The Mediterranean littoral was a large area, even given the utility of the Mediterranean itself for transport and communication. So, a state had to sustain a significant military advantage for a significant period of time to roll up all the other states and unify the Mediterranean littoral. But, if a state did, then the only border confronting significant state power was with the Iranian plateau. A geographical pattern which could generate significant economies of scale in military effort, if and when unification was achieved.

Which it was, because the Roman Republic did sustain such a military advantage for a long period of time, winning every external war for about three centuries. Long enough, indeed, to roll up every other Mediterranean littoral state and unify the entire Mediterranean littoral under one state.

Success that blocked replication

But the very success of Rome ensured that such a unification was a one-off, as the example of Rome spread the techniques of state formation beyond the Mediterranean littoral, which never again became a closed state system.  The Umayyad Caliphate and the Ottoman Empire made notable attempts at unifying the Mediterranean littoral, but it was precisely the Sahara-flanked region of the Mediterranean littoral–not that bordering the now too-deep European state system–which they united with the Middle East. Though neither controlled the entire African coast of the Mediterranean for as long as the Romans did.

So, I agree, the fractured land hypothesis does not explain the relatively high propensity for unification of China and the effectively zero propensity for unification of Europe; or why the Roman Empire was a one-off. But the interaction between geography and its effect on the dynamics of state systems does very definitely explain those patterns.

Geography matters in history; particularly before the Growth Revolution (to use T. Greer’s nice phrase) from the 1820s onwards: for geography provided powerful, continuing constraints on human affairs. Only with steamship and railroads, from the 1820s onwards, (along with the development of telegraph systems from the late 1830s onwards) did humans develop any significant technological capacity to overcome the constraints of geography. It is not surprising that a recent study found that, prior to said Growth Revolution, geography appears to have dominated institutions in explaining the average long-run incomes of regions.

China was a relatively closed state system, with blocking boundaries, so had a high propensity to unification. The Mediterranean basin stopped being a relatively closed state system, so never repeated the Roman unification. While, once there was a European state system, it was never sufficiently bounded to be unified. All the results of the interaction of state system dynamics with geography.


[Cross-posted from Thinking Out Aloud.]

* The period of the Tibetan Empire coincided with the Sui-Tang unification, so China was already unified.


  1. conrad
    Posted August 26, 2015 at 12:52 pm | Permalink

    This might not be the most intellectual comment I’ve ever made 🙂 but this really reminds of playing Risk and how well it is set up for this sort of dynamic.

  2. Posted August 27, 2015 at 3:24 pm | Permalink

    [email protected] But I loved playing Risk: and Chinese state system dynamics are, indeed, a lot like playing Risk. 🙂

  3. Marks
    Posted September 2, 2015 at 6:44 pm | Permalink

    One wonders what would have happened in this regard had A Hilter managed to get to the Urals…and empty the ‘east’ of slavs.

    He was close enough to success in that little adventure, that it could be, as with the Romans, that one factor to propensity to unification is the ability of one state to roll over the others, and destroy their cultures at least.

  4. Posted September 3, 2015 at 1:02 pm | Permalink

    [email protected] As state capacity grew, the number of states in the European state system shrank dramatically. Hegemonic domination by Napoleon, the Second Reich and Hitler was only staved off due to key states having sufficient access to extra-European resources.

    Yes, the collapse of the Soviet Union would likely have been a “game changer”, since Hitler would have access to oil and the ability to threaten the Middle East from the north.

    The ability of one state to roll over the others is crucial — hence my point about sufficient military advantage. It is notable that this could take a considerable time to develop. My central point being that a bounded system made that both easier and more likely.

  5. Nigel Davies
    Posted September 4, 2015 at 7:04 am | Permalink

    [email protected]
    The British General Alan Brooke suggested that the German army would have succeeded in conquering Russia, if it had left it to the front line soldiers.

    It failed because the popular rebellions against teh hated Soviets were undermined by the Nazi ideology and the SS extermination teams.

    Nonetheless, this still would not have worked for teh Germans long term. The Allied invasions of North Africa, Italy and both ends of France demonstrate that Lorenzo’s key criteria had been smashed (just as 19th century sea power had smashed the Chinese system).

  6. Marks
    Posted September 15, 2015 at 6:39 pm | Permalink

    [email protected],

    There are many interesting “what ifs” that could have led to victory for Germany. These range from leaving the invasion of the Soviet Union for another year (and concentrating on the UK), given that the invasion started very late due to the Greek campaign, to the scenario you have painted.

    To my mind, that only underlines how close it really was to the sort of unification Lorenzo was writing about. Even if one of multiple things had gone the other way, it would have been Sieg for sure.

    The other point that has to be made is that the rise of this situation only took from 1933 when Germany had zero chance of doing this, to 1942, when it came within a hair’s breadth of carrying it off. I would have thought that such a short time frame should exercise a few minds.

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