There is a remarkable similarity between Afghanistan and Belgium with regard to linguistic makeup. In both countries, most of the population is divided into two roughly equal language communities, speaking languages A (Pashto or Flemish) and B (Persian or French), respectively. In both cases, A is a local language without much international standing, and is shared only with another community in a neighboring country (the Dutch of the Netherlands and the Pathans of Pakistan), while language B is shared with another, much larger country and enjoys, at least historically, great international prestige, with a literary tradition going back to the Middle Ages. Moreover, in each case language B was for many years the dominant language of government and culture, and came to be used as the primary language of the upper class of A-speakers.
In both cases, A-speakers refer to themselves by a name similar to that of the language (Pashtuns, Flemings). B-speakers, on the other hand, do not call themselves Persians or French, but, at least for those communities that have traditionally spoken the language or related dialects, have special designations (Tajiks, Walloons).
In both countries, also, the capital is located in what is historically A-speaking territory, but most of its population speaks B. A part of this B-speaking population consists of immigrants (or their descendants) from historically B-speaking territory, but a larger part is made up of descendants of A-speakers, and not only of the upper class.
It is here that the similarities end and the differences begin. The French-speaking Bruxellois of Flemish ancestry (as evidenced by their surnames) do not regard themselves as Flemings but as francophone Belgians. Together with the Walloons proper they form the French Community (Communauté française), where French refers only to language.
Persian-speaking descendants of Pashtuns, on the other hand, retain their Pashtun identity, which includes a knowledge of Pashto at least as a secondary language.
Another difference: in Belgium, the principal minority group alongside the two major groups is the German-speaking Community (Deutschsprachige Gemeinschaft), whose members regard themselves as German-speaking Belgians, not as Germans. The comparable group in Afghanistan would be those who speak Uzbek, but they are not simply Uzbek-speaking Afghans; they are Uzbeks.
We see here the effect of the Seipel line, which separates Western Europe (where citizenship is the primary hallmark of nationality) from Eastern Europe and Asia, where it’s ethnicity that matters above all.