In ninth-century China, at the height of the Tang dynasty, the government became concerned about the 1CONVENIENT of carrying around large amounts of coins in order to conduct business 2ACTION. Consequently, they devised a method of paying merchants with money certificates, which had a 3TEND to blow away. This quickly earned them the 4NAME ‘flying cash’. These certificates could be exchanged for coin money on demand at the capital. They were 5TRANSFER, merchants began exchanging them with each other instead of using coins. It was not until the Song dynasty that actual paper money was created. 6INITIAL introduced by a group of merchants and financiers, each banknote had images of houses, trees and people printed on it. These were 7COMPANY by various intricate markings, the 8IDENTIFY of which could be made only by the issuing banks, thereby making counterfeiting difficult. For this reason, they became readily accepted for payment, and their circulation increased. Then, in 1023, the government decided to withdraw the banknotes and issue government notes in their place, every one of them with a cash backing. These new banknotes could be exchanged for government-issued coins, and so could be used to buy simple groceries. As a result, the use of paper money soon became widespread.