Pashtun / Pashtunwali / Pashtunistan (catch all)

[Abu Suleyman]

I would start with Friedrik Barth, and work my way forward. I know that Barth is way outdated, and worked mostly in what is today Pakistan, and not afghanistan, but he had excellent insights into the lives, culture, and traditions of the Pashtuns (which he called by the old nomenclature of Pathans). More importantly, rather than just being an anthropologist, he was focused more on political and law questions, although they were almost all traditional.

If you have access to a database that does reference searches, you can rest assured that almost every academic study of Pashtunwali will cite him.