Indigo is a blue dyestuff that was known in ancient Egypt and India; a number of mummies have been discovered that were wrapped in an indigo-dyed cloth. Indigo was produced from a plant that was mashed and allowed to ferment in tubs of water; fermentation released the colorless indigo substance, which turned a deep blue color when oxidized. The resulting dye was used for coloring cotton and for inks. The production of indigo halted when chemical processes were developed to replicate it.