Aren't they still holding on to Northern Africa, in reality? Go to a village in Morocco and try speaking Arabic, they will be insulted that you are trying to use the language of their colonizers. Yet the governments in Morocco, Algeria, Tunisia, and what's left of a government in Libya all seem to be made up of Arabs, although I'm not an expert on the region. And Egypt is indisputably Arab today, although of course ancient Egypt (as recent as Cleopatra, at least) was not. Egypt was one of the first Islamic conquests in the 700s and has stayed Arab since.
They may have lost it for a time, but they conquered it forever, essentially, even including Western Sahara (the Bedouin de facto government there is made up of people who claim to be descendants of an Arab tribe).