So far as could be ascertained, banking operations were carried on in this country on a large scale, principally by the Government, ever since the ninth century a.d. Ma Tuan-lin, the historian of Chinese currency, speaking about the trade of China in the ninth century states: the Emperor Hien Tsung (806 to 821) issued an edict prohibiting the manufacture of copper implements such as basins and kettles on account of the scarcity of cash. At this time traders brought their coin to the capital and presented it at the official treasury, the number of strings of cash annually issued from the various mints amounting to 135,000. An order was promulgated making it binding on traders to bring out their hordes of cash and purchase goods on a large scale, so that the current coins could be increased for the benefit of commerce. During this period also, traders returning from the capital preferred light baggage and they took their money, which was cashable at any provincial treasury, in the form of paper notes. Thus the paper notes, or what was then known as flying money, was for the first time introduced into China. This arrangement continued also when the Tangs were overthrown by the Sungs; the people who were authorized to pay cash in Kaifeng, for instance, received tickets or bank drafts. They could go to any city they liked, present the ticket and receive the amount named. In provincial cities taxes were paid in cash; but the treasurer could either give cash or substitute silk or other articles in lieu of the current coin when such tickets were presented. During the reign of the first Sung Emperor the people were allowed to pay current coin to the Government treasury and receive the money in the provincial cities, on presentation of the bill of exchange - the official commission being 2 per cent. In 970 a.d. an official exchange office was established; merchants deposited money with the office, received a certificate and on presentation of the same to the treasury, received the treasurer's circular letter. The merchant was authorized to take the circular letter to the magistrate of any city, who was directed by circular to pay without any delay the amount mentioned. That this system was popular is evident by the fact that in 997 a.d. the value of these bills of exchange totalled 1,700,000 strings of cash; only twenty years later the value was 2,930,000 strings of cash.