Internet resources on the Mongol Empire usually dwell on the Mongol conquests of a huge mass of territory. Unfortunately, seldom are the reasons behind the conquests explained. One gets the impression that the Mongols were conquering for the sake of conquering to satisfy their ego of becoming the biggest land-based conquerors in world history in the Guinness Book of Records. However, this is seldom so because of the huge costs of war.

Given the relatively small population of the Mongols (less than 3m today), even Mongolia itself should be enough. Surely, after conquering significant parts of China, it should be more than enough. Why did the Mongols still want to move on to conquer the other parts of Asia, Russia, Europe? What purpose did these territories serve them? Even if they managed to conquer successfully, it was doubtful if the Mongol population was large enough to spread throughout the conquered territories to rule and preserve their power on a long-term basis.

What reasons drove the Mongols to want to conquer such a huge territory?

  • 5
    I question your assumptions about the Mongol economic and poltical goals and motivations. Nomadic societies exploit land differently than settled/agricultural societies, and I doubt they wanted to give up their way of life just because there was an alternative.
    – MCW
    Commented Oct 21, 2013 at 18:30
  • 4
    Besides, Mongols were engaged in geopolitics. Geopolitics can be accurately described (I'll stop before I sound like Harry Seldon)
    – DVK
    Commented Nov 2, 2013 at 17:04
  • 8
    I'm amazed that nobody posted anything about Ghengis' point that Mongols would fight each other unless led to fight external enemies.
    – DVK
    Commented Nov 2, 2013 at 17:17
  • What does the population of today have anything to do with the population of ~850 years ago?
    – o0'.
    Commented Feb 8, 2014 at 12:39
  • 6
    Compulsive hording. Commented Mar 13, 2017 at 19:02

4 Answers 4


Maybe someone more knowledgeable about the economics of a society like the medieval Mongols might expand on this, but to me it seems that such a civilization could generate much more income by conquering and looting new territory than what they could produce internally. This is also true to the nomadic people in the migration period some centuries earlier: Huns, Goths, etc.

Nomadic people had relatively little agriculture and industry, and a larger warrior to worker ratio than settled civilizations. Settled civilizations had more accumulated wealth which they accumulated over a relatively long period of time. So it is a lot quicker and easier to generate income by conquering their neighbors than by trading with them (what could they offer if they could not produce most of the luxury goods the richer civilizations needed?)

However, when conquering and looting new territory makes up most of your income, once you "exhausted" an area, you have to move on to find new places to conquer. This is why this system cannot be kept up for too long: once you stop, your income will drop and your economy will collapse. (similar effects contributed later, among other factors, to the collapse of the Ottoman Empire)

It is like a vicious cycle: as you grow, the cost of maintaining your empire grows, and you need to conquer new territory to raise your income, and so on. Once you stop, the bubble will burst.

The one and only people of the migration period which managed to build a strong medieval kingdom and survived as a country to this day were the Hungarians, and only after adopting the way of living of other European kingdoms and giving up their nomadic lifestyle. All others vanished as quickly as they have risen.

Note: I know there are differences between the Mongol conquests and the migration period, I used them as yet another example when most of your income comes from conquering new territory.

  • 5
    +1 "when conquering and looting new territory makes up most of your income, once you "exhausted" and area, you have to move on to find new places to conquer." Commented Oct 21, 2013 at 19:25
  • 2
    Your answer has a little paradox. The gist of your answer to the gist of the question, is "Mongols had the incentive of generating huge income for the empire, for building a large empire" ; but you also say, "you grow, the cost of maintaining your empire grows" ; and let us assume that the Mongols knew this fact. Then, if they wanted income, and income came by looting to an exhausting extent, and beyond that, cost of controlling territory strained income, then, why, did they not simply loot and go back, or move on, rather than putting effort to controlling land??
    – Rohit
    Commented Feb 11, 2015 at 13:42
  • 1
    @Rohit : I don't know, maybe something like the tragedy of the commons? Don't say every nation acts completely rationally given what information they have. Look at our current problems with the climate and non-renewable resources. A lot of countries use methods they know are unsustainable in the long term, yet they use them because it makes more profit for the short term. The Mongols were not the only ones who suffered from the conquest-driven mentality. The Roman and Ottoman empires started to rapidly lose power the moment they stopped expanding.
    – vsz
    Commented Feb 11, 2015 at 14:14
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    If we agree, that they wanted wealth, it would make more sense, to be a raiding nation, than an expanding nation. But as you put foward, that they didn't have to make sense, the discussion closes.
    – Rohit
    Commented Feb 11, 2015 at 14:26
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    @Rohit Not really a paradox: conquering and taking the spoils brings money, new areas may also pay bribes, so new conquests bring money, however keeping the territory is a constant, sometimes growing cost. Since Mongols generally destroyed local economy, famines killed significant part of population, there were less and less to take, and people learned better to defend themselves. So it makes sense to conquer places, but less sense to keep them on long term.
    – Greg
    Commented Mar 14, 2017 at 3:52

The Mongols were pastoralists. Livestock herders. As such, their culture naturally thrived on steppe (or grassland) territory. A pastoral nation is not tied to any one place, but rather moves around with its herds to find the best grazing. A militarily dominant pastoralist society will naturally attempt to take over all good grassland territory for itself.

Given that, I think a look at a map of the Eurasian steppe may prove enlightening. The green areas on the map below indicate good pasture land in Asia. Altaic pastoralists like the Mongols and Turks will naturally desire to take over all this territory possible.

enter image description here

Now let's look at a map of the Mongolian empire:

enter image description here

One thing becomes immediately obvious here: All Mongol-controlled territory was within easy reach of the Steppe. The largest incursions off of the steppe, into Persia and China, represented relatively rich settled societies. These places were wealthy enough that the Mongols could simply conquer them and place themselves into the top stratum of society to suck off the proceeds of existing empires.

  • 6
    +1 for recognizing that the Mongol didn't aim to "settle" or "rule". They were pre-modern pastoralists, with commensurate goals and values.
    – MCW
    Commented Oct 23, 2013 at 14:20
  • Those maps look to be Mercator Projections, which is really unfortunate for your point. Any chance of redrawing hem on an equal area projection? Commented Jan 31, 2014 at 4:27
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    @PieterGeerkens - I didn't draw them, and am frankly incapable of drawing a straight line with a straightedge. However, they are both linked from Wikipedia, so if you think they can be improved you are perfectly free to go there and do so.
    – T.E.D.
    Commented Jan 31, 2014 at 13:26
  • 4
    This answer sounds more correct, than the one accepted by the OP
    – Rohit
    Commented Feb 11, 2015 at 13:45
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    @curious Since you're still around, I agree with Rohit. Don't you think the check should be on this answer instead? (Tom Au's below is even better for the Mongol's themselves, although it doesn't cover the Turks and other similar empires as well as T.E.D.'s answer.)
    – lly
    Commented Mar 6, 2020 at 19:31

One reason that Genghis Khan's Mongols expanded so far as they did was because each success brought with it a new set of enemies.

Genghis Khan began by uniting the five core tribes: his own "Mongols," the Kereits, the Merkits, the Naiman, and the Tatars, accomplishing this by 1206. This earned him the emnity of several groups on the borders of the new "Mongolia," who had been allied with the other tribes. From east to west they were the Jin Dynasty (the Manchus), the Western Xia (including the Tanguts and Uighurs), and the Kara-Khitan (modern Kazakhstan). Genghis Khan had to defeat the first two and occupy the Kara-Khitan before his new country could be reasonably safe from invasion.

The last occupation caused him to want to restore the use of the so-called Silk Road, which extended through central Asia, the Middle East, and the Mediterranean. Genghis Khan sent a delegation to negotiate trade terms over this road with the Khwarezemid (greater Persian) Empire, but they interpreted his overtures as a demand for tribute, and executed his envoys, starting a war. Genghis Khan sacked several of their cities (Samarkand, Bokhara, and Urgench) before conquering this empire.

Some of his men elected to return home to Mongolia using the longer route around the western shore of the Caspian Sea. That brought them into further conflict with the Cumans (a Turkish people in South Russia), who were allied with the Khwarezemids. While fighting the Cumans near the Volga, the Mongols incurred the wrath of the Kievan Rus. (The Cuman king was the father-in-law of one of the Ukrainian princes.) So the Kievans began fighting the Mongols, who had offered them peace.

The process stopped when the Mongols ran out of enemies to fight or, to be more exact, when their remaining enemies became less threatening than the internal divisions that wracked the Mongolian empire after the death of Genghis Khan in 1227. But the pattern of Mongol conquest extended for several decades more before this happened.

  • References would earn another vote (at least). Commented Jan 31, 2014 at 4:22
  • @PieterGeerkens: There is a link to Genghis Khan in the first paragraph that serves as a factual reference for my comments. The interpretations are mine.
    – Tom Au
    Commented Jan 31, 2014 at 14:05
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    Its almost like an epic film story. You have a cool interpretation. But assuming that, the Mongols only wanted a safe haven pastoral place, and they unwantedly fell into struggles, and then accidentally , won, in most of these struggles, to the extent of domination, and complete annexation, sounds a little..... too much. These are my interpretations... to your interpretations
    – Rohit
    Commented Feb 11, 2015 at 13:53

Taken directly from Asian Topics in World History: The Mongols in World History (emphasis mine):

The first question about the Mongol conquests is: Why did the Mongols erupt from Mongolia in the early 13th century to begin their conquests of the rest of the world, creating the largest contiguous land empire in world history? There has been considerable speculation about the reasons for the Mongol eruption from Mongolia, and though there is no scholarly consensus on specific reasons, many have pointed to the causes of ecology, trade disruptions, and the figure of Chinggis (Genghis) Khan.

Ecology. In the period from 1180-1220, Mongolia experienced a drop in the mean annual temperature, which meant that the growing season for grass was cut short. Less grass meant a real danger to the Mongols’ animals, and, since the animals were truly the basis of the Mongols’ pastoral-nomadic life, this ecological threat may have prompted them to move out of Mongolia.

Trade Disruptions. A second reason often mentioned is the attempt by Mongolia’s neighbors in north and northwest China to reduce the amount of trade with the Mongols. Since the Mongols depended on trade for goods that they desperately needed – such as grain, craft, and manufactured articles – cessation of trade, or at least the diminution of trade, could have been catastrophic for them. The attempts by the Jin dynasty, which controlled North China, and the Xia dynasty, which controlled Northwest China, to reduce the level of trade that the Mongols could expect, created a crisis for the Mongols. Unable to obtain goods that they so desperately needed, the Mongols’ response was to initiate raids, attacks, and finally invasions against these two dynasties.

Chinggis Khan’s Personal Mission. A third explanation has to do with Chinggis Khan himself, in particular his shamanic beliefs. It is said that Tenggeri, the sky god of the Mongols, gave Chinggis the mission of bringing the rest of the world under one sword – that is, bringing the rest of the world under the shamanic umbrella – a mission that may have motivated Chinggis to begin his conquests. Whatever the explanations, they all gravitate around the figure of Chinggis himself. Thus it is important to see what Genghis’ policies led to and to analyze his life and career.

Source: Asian Topics in World History: The Mongols in World History was produced by the Asia for Educators Program at Columbia University, with consulting faculty member Professor Morris Rossabi. The transcript is here.

  • I get that the bias is theirs, not yours, but wanting something doesn't mean needing something. Even grain wasn't necessary for pastoralists, except as a knockon effect of the climate change. Sad such a good source completely overlooks the real answers given by TED (violent society that wanted control of the best fields) and Tom Au (specific incidents in Temujin's life) in favor of trendiness.
    – lly
    Commented Mar 6, 2020 at 19:44

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