If you can travel to ancient times, what can be the most valuable thing in ancient times now?

If you put it in troubled times, of course, it is a weapon such as a gun, because with advanced weapons, you can advance and retreat and defend in a war-torn year. If it was in the Millennium, it should be an adult product now, because most emperors in the old society were lewd. If you use this kind of goods to win the joy of the emperor, it is definitely the most valuable capital in the ancient society ruled by man.