 The battles between the Song and the Jin spurred the invention and use of gunpowder weapons . There are reports that the fire lance , one of the earliest ancestors of the <unk> , was used by the Song against the Jurchens besieging De 'an ( <unk> ; modern <unk> in eastern Hubei ) in 1132 , during the Jin invasion of Hubei and Shaanxi . The weapon consisted of a spear attached with a flamethrower capable of firing projectiles from a barrel constructed of bamboo or paper . They were built by soldiers under the command of Chen Gui ( <unk> ) , who led the Song army defending De 'an . The fire lances with which Song soldiers were equipped at De 'an were built for destroying the wooden siege engines of the Jin and not for combat against the Jin infantry . Song soldiers compensated for the limited range and mobility of the weapon by timing their attacks on the Jin siege engines , waiting until they were within range of the fire lances . Later fire lances used metal barrels , fired projectiles farther and with greater force , and could be used against infantry . 
