Tanning is one of the world’s oldest traditional arts, dating back more than 7,000 years. Located near watercourses and often some length from residential quarters due to the strong stench of animal skin, tanneries turn the hides of goats, sheep, cows, and camel into soft, rot-proof leather. The hides undergo a series of processes including hair removal, soaking, drying and rinsing before being handed over to the leather workers. Some of the ingredients of this odorous process include pigeon excrement, cow urine, fish oils, animal fats and brains, chromium salts, and sulfuric acids.
Morocco continues to thrive in the medieval tradition of leather tanning. Skins are still hauled by donkey to the souq and the tanning and dying vats continue to be constructed from mud brick and tile. Health and safety precautions for the workers in the pits have changed little over the centuries and the tanneries are structured according to the medieval guild principles. The Fassi leather, made in the Wadi Fes, has for centuries been considered among the finest in the world.