Genghis Khan understood deeply the roots of power more than anyone else. He led his horde only into battles that could be won : he avoided attacking places where his army of horsemen could become trapped. Their power could be displayed only in the steppes.
When Genghis Khan conquered more advanced nations, he assimilated their technologies. He always gave his opponents an ultimatum before the battle and if they did not surrender, he proceeded with burning down the towns. This practice facilitated him with his future enemies: as his reputation grew, more cities gave up without a fight. He assimilated men from other cultures as equals. This made his army grow vastly. He did not impose anything on them in any aspect of life. He let the local monarchs rule their people as they wished. They paid him a tribute which got distributed among the chiefs and soldiers. If a new nation got conquered everybody shared the spoils.
Genghis Khan allowed social progress, encouraged education, let different religions and ethnics prosper simply because he understood that it would make the empire he built much stronger. He lived by the rule that what was conquered by power could not be ruled by power alone.