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In page Mongol invasion of Kievan Rus':

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Then he (Genghis Khan) sent Dorbei the Fierce off against the city of Merv, and on to conquer the people between Iraq and the Indus. He sent Subetei the Brave off to war in the North where he defeated eleven kingdoms and tribes, crossing the Volga and Ural Rivers, finally going to war with Kiev.[citation needed]