>>- Mongols had the largest ever empire in land mass, stretching from Korea to Poland and Russia to China.
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>>- having a military completely based on light calvary, made them extremely mobile and hard for other armies to fight
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>>- though a rustic civilization (based on herding with no cities) they would quickly embrace any military or other technique that could give them an advantage be it gunpowder, catapult, currency or writing
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>They didn't learn the dangers of quickly embacing new technologies. Kubla (sp?) Khan built and lost the largest invasion fleet of ancient times.
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>Stick with what you're good at until you learn something else enough to be good at that.

Kublai was a better diplomat than general. This is why the empire peaked then went into decline during his reign. In fact, he only effectively ruled 1/4 of the empire. As well, they weren't sailors. Also the weren't as good as the Samurai for fighting in close quarters, which was necessary to establish a beach head. Throw in a typhoon and the rest is history.