A little indigo, a handful of ash and time.
The dye pits in Nigeria's ancient northern city of Kano are said to be the last ones of their kind after five centuries of existence.
Many pits at Kofar Mata appear to be abandoned as the sons who inherit the tradition decide to pursue government jobs or other business instead, forgetting the skills passed down through generations.
The men who remain, squatting over the pits with sturdy gloves and endless patience, produce the intensely blue fabrics that are internationally renowned.
The homespun cloth, hung to dry on razor wire topping the walls around the pits, ranges from sky blue to darkest night and comes in romantically named designs: moon and shadow, moon and star, three baskets (standing for wealth, education and power).
The dye pits, founded in 1498, attracted travelers and traders from across the vast Sahel region to the Kano emirate, helping to make the city one of the most prosperous in West Africa at the time.
The fabrics are still used today by the nomadic, well-wrapped ethnic Tuareg, whose skin often takes on a blueish tinge from the dye that hasn't been "fixed."
"This is eroding culture. It's taking away market and it's increased unemployment in some sectors."
For those seeking something flashier than the mallet-pounded homemade fabrics, a separate area in the back is for dyeing finer cloth from packages stamped "Made in Germany" or Britain, at prices of 25,000 naira (USD 69), which is purchased by Nigeria's so-called "big men."