Genghis's Khan's Mongols were known for their brutality, but historians debate to what extent Mongol propaganda rather than fact is responsible for this. David Nicole wrote in his work ''The Mongol Warlords'': "terror and mass extermination of anyone opposing them was a well-tested Mongol tactic." The alternative to unconditional surrender was total war. His battles with [[China]] were extensive, and he would reportedly count the number of enemy casualties by having his victorious soldiers each cut off an ear from the fallen and bring them back to him. Genghis based his powerful army on [[meritocracy]]. Historians consider Genghis Khan a military genius. Genghis' horse armies were able to travel further in a day than any other army until the development of automobiles.<ref>Encyclopedia of Military History, Dupuy & Dupuy, 1979</ref>
[[File:Mongol1.jpg|thumb|280px|This is probably a copyrighted textbook cover but we don't care.]]
Genghis Khan was a tolerant leader in religious matters who did not influence religious practice by his subjects. All he demanded was total obedience in temporal matters. Those who did not obey faced stiff penalties, usually execution. Ultimately, the states that succeeded his empire withered and died largely as a result of the Mongols' failure to develop conquered economies, and failure to choose a religion upon which to base their state and society (and resulting overreliance on an arcane set of tribal customs).