underwent a different semantic shift and became synonymous with 'cannon.' Fire arrows are the predecessors of fire lances, the first firearm. Firecracker: The predecessor of the firecracker was a type of heated bamboo, used as early as 200 BC, that exploded when heated continuously. The Chinese name for firecrackers, baozhu, literally means "exploding bamboo." After the invention of gunpowder, gunpowder firecrackers had a shape that resembled bamboo and produced a similar sound, so the name "exploding bamboo" was retained. In traditional Chinese culture, firecrackers were used to scare off evil spirits. Fire lance: The fire lance was a proto-gun developed in the 10th century with a tube of first bamboo and later on metal that shot a weak gunpowder blast of flame and shrapnel; its earliest representation comes from a painting found at Dunhuang. The earliest confirmed employment of the fire lance in warfare was by Song dynasty forces against the Jin in 1132 during the siege of De'an (modern Anlu, Hubei Province), where they were used to great effect against wooden siege towers called "sky bridges": "As the sky bridges became stuck fast, more than ten feet from the walls and unable to get any closer, [the defenders] were ready. From below and above the defensive structures they emerged and attacked with fire lances, striking lances, and hooked sickles, each in turn. The people [i.e., the porters] at the base of the sky bridges were repulsed. Pulling their bamboo ropes, they [the porters] ended up drawing the sky bridge back in an anxious and urgent rush, going about fifty paces before stopping." The surviving porters then tried once again to wheel the sky bridges into place but Song soldiers emerged from the walls in force and made a direct attack on the sky bridge soldiers while defenders on the walls threw bricks and shot arrows in conjunction with trebuchets hurling bombs and rocks. The sky bridges were also set fire to with incendiary bundles of grass and firewood. Li Heng, the Jin commander, decided to lift the siege and Jin forces were driven back with severe casualties. Fireworks: Fireworks first appeared in China during the Song Dynasty (960–1279), in the early age of gunpowder. The common people in the Song era could purchase simple fireworks from market vendors; these were made of sticks of bamboo packed with gunpowder, although grander displays were known to be held. Rocket propulsion was