How did Afghanistan, which was overrun and ruled by a series of foreign dynasties for more than a thousand years, become renowned as the "graveyard for empires" in the nineteenth and twentieth centuries…?
…How did a ruling dynasty established in 1747 manage to hold power over such a fractious people until 1978, and why has the Afghan state since then experienced such difficulties in reestablishing a legitimate political order?
Both of those questions are from the new and excellent book Afghanistan: A Cultural and Political History, by Thomas Barfield. Most of all this is a conceptual treatment of the history of the country and its different regions. The book's home page is here.