In the foreign exchange market and international finance, a world currency, supranational currency, or global currency refers to a currency that is transacted internationally, with no set borders.
Historical and current world currencies
Spanish dollar (17th – 19th centuries)
In the 17th and 18th century, the use of silver Spanish dollars or "pieces of eight" spread from the Spanish territories in the Americas westwards to Asia and eastwards to Europe forming the first worldwide currency. Spain's political supremacy on the world stage, the importance of Spanish commercial routes across the Atlantic and the Pacific, and the coin's quality and purity of silver helped it become internationally accepted for over two centuries. It was legal tender in Spain's Pacific territories of the Philippines, Micronesia, Guam and the Caroline Islands and later in China and other Southeast Asian countries until the mid-19th century. In the Americas it was legal tender in all of South and Central America (except Brazil) as well as in the US and Canada until the mid-19th century. In Europe the Spanish dollar was legal tender in the Iberian Peninsula, in most of Italy including: Milan, the Kingdom of Naples, Sicily, Sardinia, the Franche-Comté (France), and in the Spanish Netherlands. It was also used in other European states including the Austrian Habsburg territories.