having or showing a very abnormal or sick state of mind the movie's villain was a just a clichÃ©d axe-wielding nutcase with a maniacal laugh Synonyms balmy, barmy [chiefly British], bats, batty, bedlam, bonkers, brainsick, bughouse [slang], certifiable, crackbrained, cracked, crackers, crackpot, cranky [dialect], crazed, crazy, cuckoo, daffy, daft, ...
His great empire stretched from central Russia down to the Aral Sea in the west, and from northern China down to Beijing in the east. On August 18, 1227, while putting down a revolt in the kingdom of Xi Xia, Genghis Khan died.
From a psychological point of view I rather doubt that Genghis Khan started on his road to world domination for religious reasons (as some other answers suggest). More plausible is that he and his tribe were fighting for survival. When the Mongolain internecine struggle was over he found himself in control of a superb military machine.