In 1750 BC, a man named Nanni bought copper from a Babylonian dealer named Ea-Nasir. The copper was garbage. So Nanni carved his rage into a clay tablet and had it delivered. It survived 3,770 years. It is the oldest written complaint on Earth, and it tells you exactly how ancient trade worked. Here is the wild part. There were no banks, no contracts you could sue over, no shipping insurance. Long distance trade ran entirely on reputation and trust. A merchant like Ea-Nasir built a network by being reliable. Cheat one customer and the whole city heard about it. So Nanni was not just venting. He was doing economic warfare. A bad review in 1750 BC could end your career, because your name was your only collateral. Copper itself traveled insane distances. It came from Oman, sailed up the Persian Gulf, and passed through traders in Dilmun (modern Bahrain) before reaching Mesopotamia. No coins existed yet. People paid in weighed silver, barley, and promises recorded on clay. And we know all of this because one angry customer refused to let it go. The tablet is in the British Museum right now. Ea-Nasir has been roasted for nearly four thousand years and he has no idea.