Answer:
(European) goldsmiths
Explanation:
European goldsmiths (Italian goldsmiths were the first) formulated a principle that only 5% of deposits were needed in reserve at any particular time, therefore they could lend 95% of the gold they held in deposit.
Goldsmiths would rent space in their vaults that allowed other people to keep their gold in a safe place. That led to transactions were notes indicating the amount of gold deposited would be traded instead of trading gold itself.
Eventually goldsmiths discovered that they could trade (lend) more money than the amount of gold they held in deposits, inventing fractional reserve banking.
