In a lot of old drawings and depictions of the early medieval period you see folks with brown leather belts, brown sheaths and brown coin purses. When did people first begin to dye leather black? Was it available and affordable in medieval times?
One of the easiest ways to dye leather black is to use what is called lamp black. It's produced by burning fat, oil, tar, or resin. Incredibly cheap and simple to make, it's also light fast once applied. This was one of the pigments used in Lascaux cave paintings from pre-historic times, so it was certainly available in the medieval period.