Answer: China

Long before Europeans were using printed currency, and even longer before sophisticated printing presses were running in the New World, the Chinese were happily using paper money.

During the 7th century Tang Dynasty, the precursor of paper money appeared when merchants began using a system of receipts to alleviate the need to transport heavy coinage between warehouses and stores. By the 11th century, during the Song Dynasty, the government realized the utility of centralizing the production of these promissory notes and extending their use beyond the merchant class.

By the end of the 13th century, the Chinese currency system had evolved to closely resemble what would be the standard for paper-based currencies for many centuries to come. The paper currency was backed by gold and silver reserves, printed in no less than six ink colors, used intricate designs, and it was sometimes made of special paper with embedded fibers to avoid counterfeiting.