Unlike Hitler, Genghis Khan wasn't a bigot.
In most cases the populations that he conquered experienced more freedoms under Mongol rule than they did under their previous local regimes.
While he and his troops had no qualms about the wholesale slaughter of entire cities and societies, they also did not engage in religious persecution and elevated scholars and engineers above aristocrats in their holdings.
Genghis Khan himself only conquered to modern day Pakistan, I believe. He didn't start conquering outside the Mongol steppes until he was around 50 years old. The Japanese and the Afghans were the only societies that his hordes were unable to conquer. The Europeans got totally ran through.