In medieval Europe, coins were hard to come by:
Prices after 800 AD were calculated largely in terms of an old Carolingian currency that no longer existed (it was actually referred to at the time as “imaginary money”), but ordinary day-to-day buying and selling was carried out mainly through other means. One common expedient, for example, was the use of tally-sticks, notched pieces of wood that were broken in two as records of debt, with half being kept by the creditor, half by the debtor. Such tally-sticks were still in common use in much of England well into the 16th century. Larger transactions were handled through bills of exchange, with the great commercial fairs serving as their clearing houses. The Church, meanwhile, provided a legal framework, enforcing strict controls on the lending of money at interest and prohibitions on debt bondage.
Of course, Europe was an economic backwater then:
The real nerve centre of the Medieval world economy, though, was the Indian Ocean, which along with the Central Asia caravan routes connected the great civilisations of India, China, and the Middle East. Here, trade was conducted through the framework of Islam, which not only provided a legal structure highly conducive to mercantile activities (while absolutely forbidding the lending of money at interest), but allowed for peaceful relations between merchants over a remarkably large part of the globe, allowing the creation of a variety of sophisticated credit instruments. Actually, Western Europe was, as in so many things, a relative late-comer in this regard: most of the financial innovations that reached Italy and France in the 11th and 12th centuries had been in common use in Egypt or Iraq since the 8th or 9th centuries. The word “cheque”, for example, derives from the Arab sakk, and appeared in English only around 1220 AD.