[agurk]

Looking at the wikipedia page for bank notes[0] there is no mention of salt or Bruges on the page. It suggests that bank notes first originated in China during the 7th century the knowledge of which European explorers introduced to Europe in the 13th Century. There is mention of cloth being used in Prague in 960 and the Knights Templar, as in the original article here, in 1150.

It goes on to add more details about the introduction of banknotes to solve practical problems that would be hard to summarise, but I found an interesting read.

[0] https://en.wikipedia.org/wiki/Banknote