However, it was under the rule of the T'ang Dynasty, about 700 AD, that people began to use gunpowder. T'ang Dynasty emperors used gunpowder to put on great fireworks displays. By 904 AD, Chinese inventors saw that you could also use gunpowder for a powerful weapon. First the army used gunpowder in the form of rockets. They put small stone cannonballs inside bamboo tubes and shot the cannonballs out by lighting gunpowder at one end. This is the same idea that makes guns and cannons work today. The Chinese emperors tried to keep their discovery secret, but by the 1100s AD their secret had gotten out, and people in the Islamic Empire and then the Roman Empire began to understand how to use gunpowder for weapons. After that, it wasn't long before people in Europe also learned how to use gunpowder. We aren't sure exactly how they found out, but it might have something to do with the Third Crusade. By 1216, AD, a monk named Roger Bacon in England described gunpowder as a weapon. He thought of it as something that came from foreign places. Unfortunately for the people of West Africa, they hadn't heard about gunpowder yet when European people attacked them in the 1400s AD, which is one reason the Europeans were able to defeat them. Gunpowder was quickly put to use by the reigning Sung dynasty against the Mongols, whose constant invasions into the country plagued the Chinese throughout the period. The Mongols had enough of this. Therefore, they captured the Chinese alchemist so they too could master this lethal…