The more frequent solution is to adopt some sort of credit system. When much of Europe “reverted to barter” after the collapse of the Roman Empire, and then aga

The more frequent solution is to adopt some sort of credit system. When much of Europe “reverted to barter” after the collapse of the Roman Empire, and then again after the Carolingian Empire likewise fell apart, this seems to be what happened. People continued keeping accounts in the old imperial currency, even if they were no longer using coins.