Sulphur or sulfur is a chemical element, that forms solid bright yellow crystals. It is known to mankind since around 6000 BC and was used since the Ancient Ages for fumigation, medicine, and bleaching cloth. It is one of three components required to make gunpowder, the other two being saltpeter and charcoal. As such, it was known in China after the mid-1st century AD and in the Middle East some time after 1200 AD.