A Sudanese dagger with a silver coin

[Flavio]

Hi all,
This is my last purchase: it's a sudanese dagger (meaning for Sudanese all the zone to south of the Sahara). The handle is made of ironwood and on the heel of the handle there is an arab silver coin. It's quite normal to find a coin on the heel of these daggers, but my question is: someone recognizes this particular coin? The provenience and the dating? The blade is of good iron/steel with some chipping on the edge and the tip bent and beaten again.