THE HISTORY OF TRADING — CHAPTER 01 A Clay Ball in Uruk Around 3300 BCE, a merchant in Uruk did something odd. He sealed clay tokens — cones, spheres, discs, each representing grain, oil, livestock — inside a hollow clay ball (archeologists call it a bulla). Then he pressed the same shapes into the outside before it dried. He'd just made one of the world's first receipts. Two records of the same transaction: one sealed inside, one visible outside, so the recipient could verif