It wasn't long before the Chinese made round coins out of metal.
The very first coins often had holes in tham 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 heads of various gods and emperors stamped on them to shoe they were real.
A few hundred years later leather was used as money in China, and 806 AD the first paper banknotes were produced by the Chinese.
It was still many years before paper currency appeared in Europe.
There centuries passed before it was used in all European countries.