Short answers, pulled from the story.
Currency originated in ancient Mesopotamia and Ancient Egypt, where grain stored in temple granaries was represented by metal receipts. This system formed the basis of trade across the Fertile Crescent for over fifteen hundred years.
Premodern China introduced paper money in a gradual process lasting from the late Tang dynasty (618-907) into the Song dynasty (960-1279). A standard, uniform government issue of paper money did not become an acceptable nationwide currency until the mid-13th century.
Sweden introduced paper currency on a regular basis in 1661. The country's abundance of copper had led to coins so heavy they sometimes weighed several kilograms, making paper a practical alternative.
The Nixon shock was the United States' decision in 1971 to end its link to gold, making it one of the last major countries to abandon the gold standard. No country today operates an enforceable gold or silver standard currency system.
According to SWIFT's estimates for April 2026, the U.S. dollar accounted for 50.61% of world payments. The euro ranked second at 21.60%, and the pound sterling third at 6.95%.
Polymer banknotes are currency printed on a plastic substrate rather than paper, developed by Australia's Commonwealth Scientific and Industrial Research Organisation in the 1980s. They entered circulation on Australia's bicentenary in 1988 and are now used in over 20 countries, with dramatically longer lifespans and reduced counterfeiting.