|"...and then he nailed my head to the floor. Which was fair enough."|
Born a minor nobleman he worked out that he best way to stop his people's tribes from fighting each other (which they had been doing for centuries, to no-ones' good at all) was to join together (under him, natch) and go and pick a fight with the entire world!
A distinctly old-fashioned leader, with a strong viewpoint on people who disagreed that he was the person best placed to rule the entire world.
If you agreed with him on this and were loyal to him, he was loyal to you; often employing you as an artisan, clerk or farmer to build his capital city. You could expect a pretty good life, safe in the knowledge that no-one else's marauding army could come along and give you a shoeing without having old Genghers to deal with first.
On the other hand, if you or your city elders felt that, frankly, his right to rule everything was perhaps a little overstated you could expect no mercy at all.
He even went as far as to divert rivers straight through peoples' towns just to make sure. He executed one enemy by pouring molten silver into his eyes and ears. This was an unusual alternative to the more normal Mongol practice of boiling your enemy's generals alive. If he liked you but still needed you dead, you could look forward to being crushed to death or having your back broken. Which was nice of him.
His personal politics have been described as slightly to the left of Charlton Heston.