Ever heard of “flying cash”? No, it’s not an over-marketed form of frequent flyer miles, but one of the oldest recorded uses of paper money, introduced along the Silk Road around 800 CE. True to its airborne moniker, “flying cash” took off among Chinese merchants because it made transacting, especially over long distances, much easier than with cumbersome government-issued metal coins. The name came from the paper notes’ tendency to blow away in the wind, but could have also referred to the Chinese government’s repeated attempts to blow it out of popular use. Despite its efforts, the utility of the revolutionary technology proved too great, and eventually the Song Dynasty capitulated, issuing its own paper notes in 1024 CE.