i've never been there, nor met an afghan, but my understanding is that, despite divisions in language, ethnicity and sect, there is a core of "afghan-ness" - a sense of shared history, cultural pride, desire for indepedence from outside powers, etc. it seems to me the kind of nation best described as a confederation where the many groups feel a simulateous collective and seperate identity.
canada has 2 national languages and plenty of divisions too, no? doesn't mean it can't function as a corporate entity.
Belgium. Switzerland.