he earlier campaigns of nomads was that Genghis so thoroughly established the tactics and strategy for conquest that when he died, his military heirs were able to successfully continue the campaign without his presence.
Durant writes that Genghis's genius for organization and unifying, as well as his willingness to use brutality, were demonstrated at an early age: "From the age of thirteen he began to weld the Mongol tribes into one, and terror was his instrument." Durant suggests that a challenge from the Chinese Emperor Ning Tsung was the origin of what became the Mongol conquest of China:
When he received a letter from [Tsung] demanding his submission, he spat in the direction of the Dragon Throne and began at once his march across twelve hundred miles of the Gobi desert into the western provinces of China.... His successors, Ogodai, Mangu and Kublai, continued the campaign with barbaric energy (Durant, 1963, p. 763).
One tactic used successfully again and again showed Genghis's military brilliance:
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