In 9th century China during the Tang dynasty, experimenting alchemists mixed saltpeter (potassium nitrate) and sulfur together, looking for an elixir of immortality. When set aflame, it gave off a violent reaction. They didn't find immortality, but gunpowder was effectively put to use in war c. 1044. By this time, gunpowder was used to ignite siege engines, incendiary bombs, smoke bombs, grenades, fire arrows, and even land mines. This knowledge was eventually passed on to Chinggis Khan, who hired Chinese tacticians to come up with effective tools of warfare. By this point, rocketry and even the first gun (somewhat of a flamethrower with flying shrapnel) was innovated. These advances in military weaponry added greatly to how wars were fought, even in todays times.