Why not "Couscous is a dish from Northern Africa."

Not certain the definite article needs to be omitted in English?

In US English, we would sometimes say "a dish of North Africa, Would that be acceptable in French?

I heard, "Le couscous, c'est un plat d'Afrique du nord." There seemed to be a pause after "couscous" and then another "s" sound -- to me that means a comma and a new clause...

My translation was "Couscous is a North African dish." It was marked wrong. Why? Now I've lost a heart.