The Routledge companion to marketing history - History of marketing in India

India has a fairly diverse geography and climate, and the nature of commercial activity in the littoral towns differed considerably from that in the interiors. There is evidence in the literature of the prevalence of multiple currencies or modes of exchange in the same region. The Bengal Sultanate of the thirteenth to sixteenth century ce had two such currencies – a high value and relatively pure silver coin called tanka, which was used for trade and transactions with the government, and lower value cowry shells that were used for day-to-day transactions