Changes

During the 11th century, China produced perhaps as much as 125,000 tons of iron a year, more than twice the total output of Europe, using coke (refined coal) as fuel for piston-driven blast furnaces (blast furnaces driven by water-driven bellows would not be invented in Europe until after 1300). This iron production dropped off dramatically after the Jurchen invasion of 1127, however.<ref>''Crossroads and Cultures'', 382.</ref>

During the 11th century, China produced perhaps as much as 125,000 tons of iron a year, more than twice the total output of Europe, using coke (refined coal) as fuel for piston-driven blast furnaces (blast furnaces driven by water-driven bellows would not be invented in Europe until after 1300). This iron production dropped off dramatically after the Jurchen invasion of 1127, however.<ref>''Crossroads and Cultures'', 382.</ref>

In the late 10th century, private merchants in western China began to issue their own private forms of bills of exchange, which customers could then exchange at agents in other regions for actual coinage, or for goods and services. These were replaced in [[1024]] by the government's establishment of an official system of paper money, the first paper money in the world.

In the late 10th century, private merchants in western China began to issue their own private forms of bills of exchange, which customers could then exchange at agents in other regions for actual coinage, or for goods and services. These were replaced in [[1024]] by the government's establishment of an official system of paper money known as "[[flying cash]]," the first paper money in the world.

By the 1020s, the Song government was minting far more coinage than any previous dynasty. In the 1070s, it was producing nearly 6 billion coins per year, a process which required 9600 tons of copper each year. But even this volume of coinage could not fulfill the needs of the economy, and so paper money continued to play a large role.<ref>''Crossroads and Cultures'', 385.</ref>

By the 1020s, the Song government was minting far more coinage than any previous dynasty. In the 1070s, it was producing nearly 6 billion coins per year, a process which required 9600 tons of copper each year. But even this volume of coinage could not fulfill the needs of the economy, and so paper money continued to play a large role.<ref>''Crossroads and Cultures'', 385.</ref>