The photo, by photographer Edmond Fortier, shows the Dioula warlord Samory Touré wearing on his head a plain fringed indigo headscarf called a diisa. In a brief discussion of these distinctive cloths in his book Textiles du Mali (Bamako 2003) Bernhard Gardi suggests these cloths were usually a mark of rank. Similar cloths, worn around the hips by young Dogon men, are seen in the photo below, also by Fortier.
And by a Wolof trader below:
Looking at the group of long fringed cloths from Burkina Faso that I posted on my site last week, one of which is shown below, and the remainder here, it seems likely that the tie-dye patterned examples form a previously unnoticed regional variation on this wider tradition of men’s prestige cloths.