I know of taxes being paid as a percentage of harvest, but was this a common practice? What happened to all the dry goods the government collected? Did merchants of the time also pay in some of their goods, or did they pay with cash?
Also, have taxes been paid in other ways, such as labor or conscription, or was that reserved for people who refused to pay their taxes?
Which part of the world?
IIRC it usually follows widespread monetization of exchange. Like using currency for everyday small exchanges as well as large sums.