NOVA: Tea and restaurants are certainly two important gifts the Song people gave to the world. What were some of the other Chinese inventions of this period that had a profound influence on the course of civilization?
Yates: Gunpowder completely transformed the way wars were waged and contributed to the eventual establishment of might over right. In my own research, I have been able to refute the common notion that the Chinese invented gunpowder but only used it for fireworks. I'm sure that they discovered military uses for it. I have found the earliest illustration of a cannon in the world, which dates from the change-over from the Northern Song to the Southern Song around 1127, which was 150 years before the development of the cannon in the West. The Song also used gunpowder to make fire lances - actually flame throwers - and many other gunpowder weapons, such as anti-personnel mines, which are thankfully now being taken out of general use.