Qian le - means, money on local Beijing's Mandarin street jargon.
Around 650 AD, the emperor of China began to issue paper "value tokens" for general use. As Marco Polo reported enthusiastically in 1275, "I tell you that people are glad to take these tokens, because wherever they go in the empire of the great Khan, they can use them to buy and sell as if they were pure gold".
Europeans had to wait until the 17th century when Sweden took the lead in issuing paper currency. Other countries gradually followed the Swedish example.
Photo taken in Beihai, upper Temple of White Pagoda.