These seals contain the writing that we still can't decipher and a number of fantastic designs, many featuring animals and monsters. One of the most famous and frightening is of a man with what looks like water buffalo horns on his head, sitting cross-legged between a tiger and a bull. We don't know what's really going on here, but it's safe to say that this was a powerful dude because he seems to be able to control the tiger. How did these seals let us know that they traded? Well, because we found them in Mesopotamia, not the Indus Valley. Plus, archaeologists have found stuff like bronze in the Indus Valley that is not native to the region. So what did they trade?