 A sophisticated economic system in imperial China gave birth to inventions such as paper money during the Song Dynasty (960–1279).The invention of gunpowder during the mid 9th century led to an array of inventions such as the fire lance, land mine, naval mine, hand cannon, exploding cannonballs, multistage rocket and rocket bombs with aerodynamic wings and explosive payloads.With the navigational aid of the 11th century compass and ability to steer at high sea with the 1st century sternpost rudder, premodern Chinese sailors sailed as far as East Africa.