Location can mean a lot to a film. It means almost everything to "Mongol." The vast, rolling plains with the vague outline of snow-capped mountains in the background; a solitary man, or three, on horseback, isolated in that huge panorama. There is enough drama in the landscape to make three movies. And this is just what Sergei Bodrov is planning to do. The Russian director is making a trilogy about the life of Genghis Khan. This is Part One.