Djembe is quite big and heavy instrument, so if you plan to move around with it, say take it from home to rehearsal/lessons, you absolutely need a bag.
Some thin canvas bags only enable you to carry around the instrument, but this Meinl bag also offers plenty of protection. The outer material is sturdy, and there is some padding inside. The drum head is the most vulnerable part, and the top of the bag is rigid, offering some additional protection.
Plus, it is nice that the bag has both straps for carrying on the back, as well as the handle for carrying in one hand.
On the side of the bag is a little pocket for smaller items. Bigger things like notes and sheet music can be put inside with the djembe.