I heard a report that in northern Tanzania they are using cell phone credits in lieu of traditional money. If you want to pay for something, just make a call to the provider and transfer cell phone credits to the other trader’s account. Why should those credits be any less liquid than currency? They are easier to store and transfer and just about everybody uses them.
Monetary economics in Africa is very, very difficult. It must start with the presumption that money is the asset with the highest carrying costs, if only because your relatives find it so easy to take away from you.