the next development was in 1000 BC, when china startend making bronze and copper cowrie shells. It wasn't long before the Chinese made round coins out of metal. The very first coins often had holes in them so that people could pass a piece of string through them to keep them together. By 500 BC metal coins had begun to appear in countries like Persia and Greece, and later in the Roman Empire. These were usually lumps of silver with the heads of various gods and emperours stemped om them to show they were real.