In order to theoretically analyze, from the perspective of new monetary economics andsociallearning,theevolution of monetary arrangementswith functional separation of money,thispaperanalyzes the history of Hanseatic monetary arrangements and the functional separationof money in the Baltic and North Seas region, that is, the evolution of units of account andmedia of exchangealong the East-West trade routes of the Hanseatic League. Focusing on thecognitive aspect of money as social institution, the evolution of units of account and media ofexchange are studied as adaptive responses by human minds. The emphasis will be on theheuristics of long-distance traders in the Baltic and North Seas region, considering theexchange of commodities and of monies.Going beyond the emergence of money as mediumof exchange, this paper studies the emergence of unitsof account and of media of exchange,that is, the emergence of monetary arrangements as co-evolution of units of account, in theMiddle Ages called monies of account, and media of exchange, in which the value of moneyis given by its purchasing power, be it money of account or money as medium of exchange.This paper views institutions as having both a cognitive and a behavioral component. Associal institution, money has a cognitive dimension, which represents the way traders thinkabout money as unit of account and medium of exchange, respectively, in the form ofmonetary heuristics, translating the unit of account to a particular worth, using a social scriptto which market agents attribute a specific worth.When the value of the underlyingcommodity bundle changes from the original worth, market agents observe a script deviationof that bundle, attributing that to changes in the commodity space, and adjust the bundleaccordingly. As social institution, money also has a behavioral dimension, which is expressedin the purchasing power of money; what commodity bundle could be bought for a certainamount of one currency, a medium of account with its associated media of exchange, foranother currency, thus establishing exchange rates. Exchange rates between currencies wereestablished according to relative perceived purchasing power, some kind of classifier system.Along the cognitive dimension, long-distance tradersformed beliefs about the relativepurchasing power of their currencycompared with the foreign one; along the behavioral onethey exchanged money at the rates so specified.The Hanseatictrade was organized along theline Novgorod-Reval-Lübeck-Hamburg-Bruges-London, whereBruges is of particularinterest as meeting place between Italian and Hanseaticmerchants, an interface ofMediterranean and Baltic commerce.In Bruges,Italianmerchant-bankers operated, usingbillsof exchange to meet the requirements of trade by correspondence, while Hanseatic traderelied on the exchange contract adopted to traveling trade. Hanseatic merchants openedtransitory accounts with Flemish money-changers to be used as means of settlement.Amonetary market orderevolved through the exchange of money and of commodities.