As for the OP's question: if "fiat money" is to be defined as money (coin or paper) issued without the ability of converting that money into a fixed amount of precious metal, then very little of my ancient and mediaeval collection qualifies. Historically, almost all money in ancient and mediaeval times has either been made of, or been theoretically convertible into, gold or silver coin - you only needed to scrape together a large enough pile of it, and find a moneychanger who wouldn't gouge you too much.
I do, however, have one piece of ancient currency that certainly qualifies as "fiat money". The Chinese usurper emperor Wang Mang was notorious for issuing new forms of currency, backed only by the threat of imprisonment and execution for anyone who dared to refuse to accept it, only to withdraw them a few years afterwards and replace them (at exorbitant exchange rates) with a new form of fiat money.
This particular cash coin dates from his fourth and last "reform", issued circa 14-22 AD. The inscription reads "huo quan" (which I think translates to "money of value"). The reverse is blank.

Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Edited by Sap
08/26/2008 10:25 am