My response is based on my memory of this book, although I read it quite recently and am speaking in generalities, not details, so hopefully it'll be helpful.

Also how did his huge empire not fall apart so easily? I've read he was very open minded about other cultures and basically let them be without too much hassle. But I imagine most people would still rebel against him.

The main thing I got from the book in terms of his success was a dual policy of extreme (for the time - and even compared to some modern societies) tolerance of other cultures and a correspondingly extreme (even for the time) intolerance of betrayal/rebellion. Given a choice between the most benevolent dictatorship on earth and your city being exterminated down to the domestic pets, not too many will choose the latter.

Also it must take a smart man to understand how to use fear a weapon. Where did Temujin learn this along with his tactical insight.

He grew up as a fairly powerless outcast (his father, a tribal chief, having been assassinated when he was 9) watching the brutal politics and wars of the steppes. He just kept his eyes open and learnt to be the best practitioner of what was going on around him.

EDIT: This reply also references the book I mentioned and gives a much better, more detailed answer to the question. What they point out (that I didn't stress enough) is that Genghis Khan's open-mindedness is the trait behind his success, and certainly the two points I tried to make. He was open-minded enough to tolerate other cultures (chairing a debate between Christians, Muslims and Buddhists at the time of the Spanish Inquisition), which made his rule such an attractive option relative to the extremely unattractive alternative. He was also open-minded enough to learn from the world around him, not much blinded by bias and prejudge and so able to effectively solve the problems he faced (and he faced a lot of them from an early age, so got a lot of practice).

If you spend any time studying the life of Ghenghis Khan, you come to a pretty inescapable conclusion: He was unique.

As other posters have said, he was very intelligent, despite the fact he was essentially illiterate. I think his defining trait, though, was his open-mindedness.

Consider: you have a man raised in extreme poverty and violence in one of the harshest environments on earth. He should have been a small-minded, petty, abusive tyrant with no regard for "civilized" virtues such as education, tolerance, and fairness. Further, considering the social background he came from, he should have given no trust or influence to anyone not of his immediate family.

Instead, he broke virtually all the paradigms of his worldview. Uneducated, he valued knowledge. With virtually no exposure to ideas of religious freedom, toleration was the law of the land. Coming from an insular, tribal society, he rewarded and promoted based on merit, not family influence (with the notable exception of his own children).

To put this in a modern perspective: imagine a gang member from a broken home in the inner city being elected President and introducing the bill of rights, despite never having gotten his GED.

As a result, he commanded intense loyalty. Members of rival tribes who he conquered expected to be enslaved or plundered of all their goods. Instead, they were welcomed into the fold and rewarded with influence and responsibility based on their competence. They must have been tremendously relieved and grateful.

Was he brutal? By our standards, yes. But you have to understand the context- he was intensely interested in establishing trade ties with other nations, and when this was refused (as in the case of the Khwarezm Empire where his envoys were murdered by the governor of Otrar) his response was to invade and destroy his enemies with ruthless efficiency.

Where his enemies acceded to his demands to surrender, they were treated well. In most cases, their leaders and religious institutions were left unmolested.

There were certainly rebellions throughout the the period of his dynasty's rule, and these were put down ruthlessly. But, the rebellions seem to generally have been at the instigation of the local leadership. The Mongol's usual response was to wipe out the local nobility and install more pliable local rulers. The peasantry/commoners don't seem to have been to bothered by Mongol rule in most places- probably because taxation was not excessively burdensome, and people were able to enjoy a fairly high degree of law and order for the times.

Going back to my thesis that Temujin was unique, it is worth noting how his children and successors were not unique. Instead, they were very much what one would have expected Ghenghis Khan to be: small minded, self-indulgent, glory-seeking, and brutal (with a couple of notable exceptions). In other words, there was nothing about his upbringing or about Mongol society that should have engendered the qualities that he displayed- just the opposite in fact.

Sources: A history degree focused on Central Asian history and Genghis Khan and the Making of the Modern World by Jack Weatherford Empire of the Steppes by Rene Grousset

References throughout: Weatherford's book, the Russian chronicles, the Secret History, a few dozen articles and histories that I didn't like as much as Weatherford.

On tactics: Chingis was a damn good tactician, but I somewhat wonder if in pure brains he ranks. His army vastly out-teched his opponents, and then used simple strategies that really abused their tech to the fullest. His horse archers could turn while riding and shoot backwards, meaning they could not easily be pursued, and could retreat and advance at will. They were lightly armored and very, very fast, with several horses a piece, and the Mongolians were sometimes said to use human shields to reduce their own risk. Another very simple yet devastating move was to attack ferociously with skirmishers, but then have them rout - when enemies moved to pursue the retreating Mongols, they were flanked and obliterated by heavier cavalry and archers. They would herd enemy troops like animals - something they did all year round, horses and goats and sheep and yaks. And they used siege bombardment in open fields, which they had recruited/stolen from China. No one could match an army that moved very, very fast and fought mostly at long range.

On the stability of the empire: raoul is right, Mongol retribution was brutal. But it's much more than that. The Mongols established a post service, called the yam, with riders trading horses frequently to transition messages as rapidly as possible across the Empire. The roads were said to be extremely safe under Mongol rule, and they needed to be, because East-West trade was their lifeblood, the only way they could hope to not only sustain the army, but to keep the rival political families in check. Which brings us to the structure of Mongol governance - the uppermost echelons were family and friends of Chingis, that was true. But a lowly steppe conqueror didn't have political friends or political debts, his commanders were the very best, and held to extremely high standards. The new khan was elected by the aristocracy of the Empire, and was always supposed to be the very best leader. The khagan and royal family didn't micromanage the Empire, though - they mostly appointed local proxies. And by appointed, I mean (in Russia, at least) the proxy had to be approved by the local Mongolian power broker, in person, and disapproval was sometimes synonymous with execution. Moscow's prominence today is entirely because Mongol tax collectors decided they like the tune of the Muscovy princes more than others.

The Empire was massive, but it communicated, and local power answered - in blood - to Mongol oversight. The Empire wanted its treasure to flow, and it accomplished that.

However, it collapsed under internal ambition. When politics infected the royal family, and threats of assassination appeared, the kuruldai election system fell into disarray, leading to a blood conflict with each family for themselves. Kublai Khan gets to call himself khagan for two reasons - first, most of the local Mongol rulers paid obeisance to him, and second, because he controlled Mongolia. But the Empire, in the European sense, was over before he consolidated power. Batu's Horde and the Middle Eastern khanates were really independent powers.

Here is a video of a professor I knew giving a lecture on some early mongol history. He has a lot of knowledge about the history of peoples of Eurasia. I last talked to him over a decade ago but from what I recall Temujin had a hard life as a child and vowed to do things differently than the culture he found himself in. He was quite brutal with people who didn't follow his orders and got a fanatic following behind him as his power and influence grew.

One of his revolutions of how things were done on the steppes was incorporating defeated tribes into his own tribe and treating them like family. His eldest son was likely from another man but he kept him just the same (which leads to tension and may have stoked the eventual civil wars and collapse of some of the mongol regimes).

On the steps you fight when advantageous to you and run otherwise. If you route another group and they flee you get steal their stuff and looting/raping would occur in the middle of a skirmish. Your enemies would flee and you would let them as you went through their belongings.

This lead to grudges going back and forth and alliances being made and lots of constant infighting among nomadic tribes. Temujin demanded that when fighting another tribe you fight them down to the last man so that they won't be a problem later. Anyone looting before the fighting was done was severely punished.

He favored and prized skill and know how and rewarded meritorious behavior. He was also very shrewd in the politics and world affairs of neighboring nation states. There's all kinds of things that he did differently and I couldn't begin to remember it all.

If you can find Vajda's contact information I know he loves this stuff and could probably direct you to some good reading material.

edit: I think you can find it on this page