"It has been noted that the Jenghiz-Khanite Mongol invasion of the thirteenth century was less cruel, for the Mongols were mere barbarians who killed simply because for centuries this had been the instinctive behavior of nomad herdsmen toward sedentary farmers. To this ferocity Tamerlane [Timur] added a taste for religious murder. He killed from Qur'anic piety. He represents a synthesis, probably unprecedented in history, of Mongol barbarity and Muslim fanaticism, and symbolizes that advanced form of primitive slaughter which is murder committed for the sake of an abstract ideology, as a duty and a sacred mission."