The so-called “fire cannon” was a tube made of bamboo filled with gunpowder which，when fired，threw a flaming missile towards the enemy.According to a description of a battle scene in 1132，it took two persons to carry a “fire cannon”，and the cannons were fired from a moving platform.And this platform had to be moved close to the wall of the besieged(被围攻的) city.The Chinese invention of gunpowder reached Japan，the Islamic countries and then Europe in the 13th century and the Arabs improved gunpowder for military use.