Before the development of states, kingdoms, and empires, all humans were confederated into tribes. Since then, of course, things have changed. Many tribal groups banded together defined their own boundaries, and formed into states and nations.

My first thought as to why this sort of thing happened was that it was based on agriculture. Babylon and Mesopotamia rose up out of agricultural societies, after all. I'm not sure this is a good explanation though, since it seems like there are cultures that practiced agriculture but did not form such states, like the native North Americans, and also nomads who founded empires, like the Mongols.

In general, what drives a stateless, tribal society to from into larger kingdoms?

  • $\begingroup$ Note that in Mesopotamia (and Egypt), it was not only the case of introduction of agriculture but also a very rich and productive soil (due mostly to river floods). $\endgroup$
    – SJuan76
    Jan 31, 2015 at 13:13
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    $\begingroup$ There have literally been whole books written about this. Way beyond the scope of a short WB answer. Ian Morris has two books, Why the West Rules (For Now), and War What Is It Good For, whose starting chapters discuss this problem at length, for more competently than I ever could. $\endgroup$ Jan 31, 2015 at 20:26
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    $\begingroup$ Are you talking about the development of states or nations? While the media tends to use them interchangeably, they are two different things. States are a political unit with specific, defined territory. Nations are groups of people with common culture, language, descent, heritage, what have you. Nation states are when a nation and state coincide (ex. Japan). $\endgroup$
    – CoolCurry
    Feb 1, 2015 at 3:03
  • $\begingroup$ Does "tribe" mean single extended family, or several distinct families? Very different, aren't they? PBS America told me today, Genghis Khan's and his neighbours' "tribes" were really extended families, yet the "larger group" they formed became the biggest land empire the world has ever seen. That aside, don't you think major societal changes are always forced? Of course agriculture boosts the food supply, but does that lead people into larger groups before the population grows enough to bring conflict between neighbours? I suggest not. $\endgroup$ Jul 18, 2020 at 20:10

7 Answers 7


This is a great question, with serious applicability for worldbuilding at large.

Lots of useful answers so far. I've got one, if I can express it well enough, that goes down to some very basic questions about human ecology. First though, lets get some terminology down:

"Tribe", according to the general definition in the Wikipedia article means:

"A tribe is viewed, historically or developmentally, as a social group existing before the development of, or outside of, states. Many people used the term "tribal society" to refer to societies organized largely on the basis of social, especially familial, descent groups (see clan and kinship). A customary tribe in these terms is a face-to-face community, relatively bound by kinship relations, reciprocal exchange, and strong ties to place."

In other words, we can use "Tribe" to mean either

  • a pre-state form of political organization (for fairly small values of "state"), or

  • a group of people whose primary political association is based on face-to-face acquaintance and/or kinship.

This seems to match the original question's intent.

pre-"state" human bands

There are basically three kinds of associations in history that predate states and that rely on intuitive, rather than explicit, theories of political legitimacy. These three types of community are fundamentally distinguished by their ecological characteristics. They are:

  • Hunter-gatherer bands: Small, generally migratory groups, usually using paleolithic technologies. This is the human ur-state: it was the main form of human existence for most of our time on the planet.

    The hunter-gatherer life is so old that we evolved, biologically speaking, to fit its norms, and haven't evolved past it. Everything since has happened far too recently in evolutionary time. We are still fundamentally hunter-gatherers in terms of our hard-wired reflexes and mental organization... which is possibly why we hate our day jobs so much. ;-)

  • Early agricultural societies: The beginnings of agriculture probably inherited the migratory patterns of hunter-gatherer tribes. From the initial observations that seeds sown in previous wanderings would sprout as new plants, up into the slash-and-burn techniques enabled by neolithic tools that were tough enough to chop trees, moving on from one place to another was a common mode of agriculture.

    However, eventually the early agriculturalists worked out ways of staying in one place, which had incredible advantages (grain bins, clay pottery) and also severe downsides (disease due to humans and animals huddling together and no longer moving away from their excrement and refuse.) Still, in terms of Liebig's Law of the Minimum, the agriculturalist had developed ways of generating food surpluses never possible for the hunter-gatherers.

    The march of civilization had begun.

  • Pastoral nomads: Unlike the plant-eating agriculturalists who had to eventually settle down in order to take best advantage of their improved food source, pastoralists turned to a diet of animal food. They evolved a way of life that generally remained mobile, driving herds or flocks of grazing beasts to new areas of pasture.

[Note: I got most of the foregoing from The Rise of the West, by William H. McNeill; originally published in 1963, it's still in print and not freely available online. FWIW, I'd recommend it as a resource for any worldbuilder interested in the processes of prehistoric and historical development of human communities.]

Civilization emerging from the conflict between agricultural and pastoral ways of life

In late prehistoric and early historic times, we see a three-way struggle for supremacy between these three human ecologies.

The hunter-gatherers got shouldered aside pretty early. They were, in general, too close to the margin of survival to compete effectively. Those who weren't absorbed into agricultural populations were generally pushed into more remote or forbidding areas: forest or desert mostly, or the icy lands of the north.

The hunter-gatherers could live in these areas because hunting and gathering are pretty sustainable if given time to adapt. Nobody else wanted those places. Neither nomads nor agriculturalists could grow food very well in those places.

The retreat or vanishing of the hunter-gatherer people cleared the decks for a rather dramatic, millennia-long struggle between agriculture and pastoralism. Pastoralists tended to be militarily far more formidable, because keeping predators away from the herds meant that courage and violent skills were desirable characteristics. Also, once they learned to ride horses, their mobility and cavalry tactics tended to present a formidable challenge to the settlements of agricultural people.

Consider this brief list of fairly famous pastoral nomad tribal names: Scythians, Sarmatians, Parthians, Huns, Alans, Avars, Bedouin, Mongols, Seljuks, Ottomans, Tuareg, Tatars, Comanche, Sioux, Cheyenne, Kiowa... There's thunder in that list. These are names (often, of course, not names that the people themselves would have recognized) that we remember as fierce, resourceful, indomitable fighters.

The increasingly large settlements of agriculturalists, on the other hand, were at a disadvantage. Not only were they less martial by cultural training (farmers with brawling, violent temperaments are less efficient at sowing and harvesting, and cost the community more in incidental damage), they had a lot of good stuff to loot. Stuff that nomads hadn't learned to make, or couldn't make or grow.

Thus came the great aggregations. Smaller agricultural villages were too vulnerable, once the nomads appeared on the scene. So they began to grow, and build fortifications, doubling down and to make arrangements for mutual defense.

Faced with these hardened targets, the nomads also developed larger bands, but they seldom had the staying power of the settlements of civilization.

The nomads created mechanisms of joint war parties, ad hoc expeditions whose goal was to plunder a foe too large for any single nomad tribe to take on. These eventually tended to develop into habitual associations: confederacies of nomad people who sometimes didn't even have much of a common language.

Yes, there were the grand imperial ventures of Attila and Genghis Khan and Tamerlane. However, the Pax Mongolica only lasted some two hundred years, and Genghis's empire was, although vast, too closely tied to his own formidable persona. It was, in a sense, just an incredibly large instance of a "tribe", with Genghis as the titular Father figure: an ancestor that bound his polyglot empire together.

The concepts of political legitimacy that the agricultural peoples haltingly pieced together over centuries never found a very comfortable home in the wild hearts of the horse people.

So, the original question:

What determines whether or not tribes will form into larger groups?

Has this basic answer:

The hunter-gatherer peoples really seldom could. The agriculturalists and pastoralists displaced the hunter-gatherers in any lands they wished to take.

The pastoralists, even as they responded to the increasing size of agricultural opponents by increasing their own political groups into confederacies and Hordes, remained tribal at heart.

  • $\begingroup$ Great answer! I hadn't thought about the differences between how different groups of nomads go about meeting their basic needs and how that impacts civilization development. $\endgroup$
    – ckersch
    Feb 3, 2015 at 23:16

Math and Technology

Ok. First, the Math. As the area you control grows, you get a better border-to-interior ratio: Border Vs. Interior

This is because your border size scales linearly (the red line) but the interior grows with the square of your average width/length (the blue line). So the bigger you are, the easier it is to defend your territory compared to the resources you control.

Now obviously not all polities are squares (actually I'm not sure any polities are perfect squares), but geographical features act as "free" border - they increase your ratio by either reducing the resources you need to secure it, or limiting your enemies to only attack certain areas (mountain passes, natural gulfs or bays, etc).

So, bigger area = less proportional resources needed for defense. This frees up your workforce to do other things, like agriculture, pottery, or blacksmithing. Good geography gives you a boost, so you can get some of the benefits in a smaller polity.

Second is Technology. This is obviously very broad, but let's break it down into a few key areas:

  1. Population (agriculture, medicine) - these are technologies that let you either grow your population, keep more of your population alive, or free up a larger percent of your population to do non-essential things.
  2. Infrastructure (roads, canals, communication, bureaucracy) - obviously as your polity gets bigger, it gets harder to move supplies around and control things. These technologies let you move stuff around better, send marching orders or organize the larger and larger armies you're running with.
  3. Military (weapons + everything under infrastructure) - a more effective military lets you defend better, meaning you can cut down and use more people for non-essentials, or you can expand with your current military.

Feedback Loop

The real key is what happens when all the above combines. When you get a larger polity, you can defend it easier. This frees up some of your population for other tasks, which eventually leads to be better technology, improving your overall efficiency. Now you have the capability of expanding against your less-efficient neighbors (either through politics, economics or warfare). Now you're bigger, go back to step 1 and repeat.

Obviously there are a lot of places in this process where you can mess up and your empire fractures, or you run into someone else ahead of you on the curve and they take you over. But the basic feedback loop is the driver of early polity growth.

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    $\begingroup$ Your math graph is fine, but a better graph would show why empires don't grow to fill continents. $\endgroup$
    – user3082
    Jan 30, 2015 at 23:36
  • $\begingroup$ Area grows with the square of the area? That'd be a first. $\endgroup$ Jan 31, 2015 at 21:33
  • $\begingroup$ That was bad wording, adjusted. $\endgroup$ Feb 1, 2015 at 6:32

There is a wide array of reasons, but I'll focus on one of the major ones I see. In many cases, it's a single persons ambition (I should add "ambition plus luck")

  • Greece under Alexander. The Greeks found their one person to follow and united under him. Following his demise, the fight for leadership was fragmented and nobody could fill what he was

  • Mongols under Khan. It was his personal ambition that led to him conquering nearby tribes and eventually carving out the largest empire known on Earth

  • Babylon under hammurabi. Babylon was a small city state, hammurabi forced it into the spotlight and through war became the major power.

  • Huns under Attila. He uprooted his entire people and marched them across Europe...takes some personal ambition and ability to inspire to pull that off. Not quite sure if there was ever a 'kingdom' here, but same idea...a people united under one leader.


  • Rome under Caesar. It's debatable if this tribe united to kingdom...but roman prior to Caesar was a senate with ruling families. It was Caesar's ambition that united it all into one Roman Empire.

There are several examples of Vikings and their leaders carving out kingdoms for their own.

For the most case, tribes (and city states) are loyal to a single person...with no abstract concept of nationality or king or country, the loyalty is to that single person (or perhaps dynasty of people). That single persons ambition often drives the mve to kingdom.

THe other side gets into common defense...agriculture becomes a big thing simply because you now have a stable population of decent size that can remain in one area. This leads to buildings and wealth and eventually an economy...you suddenly have something you don't want to lose. But even then, it's usually a single leader that goes about uniting several like cities into a nation/kingdom.

I think a quote from the civilization series...A multitude of leaders is a bad thing, let there be one ruler, one king. How ambitious that one ruler is in becoming King tends to be the driver behind the formation of kingdoms.

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    $\begingroup$ Rome was a nation well before Caesar. Saying that it was a tribe because it was directed by the Senate is like saying that the USA is a conjunt of the Rockefeller, Kennedy and Bush tribes. $\endgroup$
    – SJuan76
    Jan 31, 2015 at 13:16
  • $\begingroup$ Caesar may have changed the politics, but there was a distinct Roman people for hundreds of years before him. And the Roman empire still contained many different tribes and peoples. Caesar in no way is related to change from tribe to nation. In fact, he didn't even create the boundaries of Rome (Rome had been conquering other areas well before him - see Greece for instance) - he changed the ruler ship from Senate to dynastic empire. $\endgroup$
    – CoolCurry
    Feb 1, 2015 at 2:55
  • $\begingroup$ Also, your other examples are... dubious. You seem to be talking about forming political units, whereas the question seemed more geared towards formation of nations (a people with a common culture and heritage, ex. the Kurds are a "stateless nation." $\endgroup$
    – CoolCurry
    Feb 1, 2015 at 2:58

I think generally it's a form of self preservation. The larger your 'group' is the better you can defend what is yours from those who would want to take if from you. If you are the biggest group in the neighborhood, then you can even go on the offensive and be the one taking from others.

One of the reasons agriculture seems to make this more obvious is two things. One: plants are stuck in one location and thus need to keep others away from a known location. The farther the boundaries the harder it is to raid what's in the middle. Two: agriculture more easily allows for larger populations to be fed. Larger populations means more people available to defend what is ours or take what is theirs.

Being a social animal also helps encourage the group dynamics.

  1. Tribes becoming sedentary

    Agriculture can be attractive for the nomads and for several reasons. Life on the plains is rough. Not only do you need to protect your livestock, but you're also vulnerable to attack from other tribes. Plus let's not forget that Mother Nature can be quite unpleasant. Agriculture gives a more reliable source of food and can be stocked for a long time if needed. Sedentary life is also usually considered less demanding for the body.

    I know this is not really true for the first cultivators. It took some time before finding the right way to farm efficiently. But eventually, agricultural societies prospered and became rich. There was a fascination about these societies in most tribes. A lot of tribes in Asia tried to emulate the Chinese in different ways. Not all decided to settle because of this, but some ended up as farmers.

  2. Tribes uniting other tribes and staying nomad.

    The first point mentioned an issue about food security. Uniting the other tribes can also provide more physical security. Multiple tribes can be in competition and might attack each other. Tribal groups are considered a threat in most agricultural societies, but also for the nomads among themselves. They all want the best horses and the best land with the best grass. Some people are just ambitious and will try to dominate others because they love power.

    I think the most important motivator for uniting the land is to assure our own tribe security. But I need to add that a charismatic and ambitious leader if often the catalyst.

  3. Finding the middle ground.

    It's not really related but the Liao dynasty, during the Song dynasty, invented an hybrid system. They managed to keep an Empire with a strong nomadic heritage while integrating the sedentary Chinese of northern China. It was always a constant fight to decide whether they would go one way or the other. The Khitan managed to keep the balance until they got invaded by another nomadic tribe.


Groups form when they are more resilient or more enjoyable than being on their own.

Survival on your own is hard. You spend most of your resources on survival. Aggregating groups cuts down on duplication, so you free up more resources to work with. Consider that each tribe needs a shaman whose entire life is dedicated to the art. However, if tribes merge, eventually they can decrease their needs from one shaman each to one shaman between them all. That makes larger groups more resilient.

However, there is another side: when you merge groups, you have to make compromises. Your particular way of sowing the field, naked as can be, may have been effective on your own, but your new found friends don't appreciate the *ahem* scenery. You have to find a new way to sow the field -- most likely clothed.

As long as the benefits outweigh the costs, groups will eventually merge together (or at least ally).

As a detail, the human mind appears to be structured to handle several particular sizes very well. Each group feels a little more alien than the last. These sizes show up in countless cultures, over structures both social and military:

  • 5 people - clique. Usually the size of the group of people you would rely on in extreme emotional stress
  • 15 people - sympathy group. Usually this is the size of group you have emotional ties to
  • 50 people - camp group. Hunter/gatherer tribe overnight camps tended to be in this size, drawn from a group of 150 people which are....
  • 150 people - coworkers. Anything larger than this, and we tend to stop associating personalities to the individuals. Instead of knowing Alice and Bob in accounting, we know "the acounting people."
  • 750 people - Megaband
  • 1500 people - Tribe. It is believed this is the maximum number of faces the human brain can recognize.

There are mechanisms that favour the apparition of nations, and other mechanis that favour its disgregation:

Three mechanisms that favour the apparition:

  • Growth: A successful tribe that has enough food supply and controls external enemies just grows to become a nation. Examples would be old Mesopotamian cities, kingdoms of Old Egypt.

  • Common interests: A group of agricultural tribes may organize themselves for defense against raiders, trade, etc. If the common interest lasts long enough that common institutions are stablished, they may become more important than local institutions. And example could have been early Roma.

  • Conquest: The more spectacular when you see it in the maps, but the less likely to stay if it is not backed by some other structures (religion in the Caliphate $^1$, law & civilization & trade in the Roman Empire). Submitted peoples are bound to revolt, and once the imperial power is in trouble due to internal infight or a successful revolt, all of the territories would launch their own rebellion. Examples would be Mongol Empire, Assirian Empire.

As for mechanisms agains the apparition of nations:

  • Supply: if your tribe grows but there is not enough food, there will be internal infighting or emigration until the numbers are reduced again. And in time of crisis, a part of a country may think that supporting the common effort is not worth the resources spent in it (it is one of the causes of nationalism being stronger in the richer regions).

  • Local loyalties: Local elites may be tempted to gain power by becoming independent. In some cases, it may be even the representatives of the central power who begin the separatist struggle.

  • Regionalims: The local people does not see themselves represented in the State, either by political discrimination (v.g. Thirteen colonies) or by being culturally different (v.g. Ulster, Quebec). This would often get feedback with the previous point.

In all of the cases, I see technology as a factor improving the apparition of states (by improving wealth, communications and trade)

$^1$ Even in the case of the Muslims, the first caliphate lasted only thirty years until the first civil war, and the second one less than 90 years. After that, a caliphate remained, but with many of their former territories independent.


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