This is a pretty one-sided presentation of the results of the Mongol conquests. The ruthlessness of the Mongol armies is not mentioned. Historians estimate that the Mongol conquests caused the extermination of perhaps 60 million people, which would have been more than 10% of the world's population. The author mentions that Persian scholars were employed by the Mongols; that may be true, but estimates are that 90% of the population of Persia was slaughtered.
In Arabia, Bagdad, probably the most civilized city on earth, was destroyed, along with its libraries, the greatest storehouse of human knowledge at the time. Arab civilization, once the light of the world, has arguably never recovered from the wreckage left by the Mongols.