Chinese Taoist alchemists combined sulphur, saltpeter and charcoal to make the earliest form of huoyao, or gunpowder, during the eighth-century Tang Dynasty. It was used to kill insects and treat skin diseases before its weaponry advantages were realized.
Emperor Wu Di financed research during the Han Dynasty for the Taoist alchemists to mix sulfur and saltpeter. The original reason for this research was to focus on secrets of eternal life. Chinese alchemist Wei Boyanghe wrote the "Book of the Kinship of the Three," which detailed the experiments. The Chinese first launched gunpowder tubes using arrows; however, they soon discovered that gunpowder tubes could launch on their own due to power from the gas that escapes.