Via open money researcher Eli Gothill:

“There are some good examples of peer-to-peer issued money in the Middle Ages in David Graeber’s book ‘Debt’, Chapter 10 ‘The Middle Ages’:

p 270: In China, bank-issued paper money was in use during the Song dynasty (960-1279 AD) but was unstable due to inflation and the ‘newly available printing press.’ During periods of collapse, people resorted to ‘tea checks, noodle checks, bamboo tallies, wine tallies, etc.’ The source Graeber quotes is Peng (1994:508, 515, 833.) Graeber also notes these forms of popular money resembled the ‘token’ money seen in Europe in the Middle Ages.

p 277: The Islamic trade routes in North Africa and across the Indian ocean used informal credit notes as money. These promises to deliver were issued by trading merchants and backed by their ‘honour’, rather than state authority. Courts existed to adjudicate disputes but they had no power to enforce decisions, only to impact on merchants’ reputations. Graeber says that checks issued in this way ‘could be countersigned and transferred’ enabling them to travel ‘across the Indian ocean or the Sahara’ as forms of payment. One source he gives is Goitein (1966, 1967, 1973) who wrote about Jewish merchants using this type of money in 12th century Egypt.

There are many other examples, including in Europe. Interestingly, I was at an exhibition on the history of money at the British museum and there was hardly any mention of the existence of these types of peer-to-peer credit notes. As Graeber suggests this might be due to the fact that no paper money from that period has survived, while some bullion has.”