Re: What literature to read about the Seljuks, Ghaznavids, Ghorids and Khwarazmians?
Morgan's Medieval Persia is a very condensed history of Iran from the fall of the Buyids to the rise of the Qajars. The narration is obviously very elementary, because not much can be said about eight centuries in just 200 pages, but the book can serve as an initial introduction to the political history of various Muslim dynasties, like the Ghaznavids, Ilkhanids, Timurdis and etc. Otherwise, if you have easy access to a large university library, you could consult the Cambridge History of Iran. The earlier volumes concern only the Antiquity (like the Achaemenids or the Arsacids), but numbers 4 and 5 describe exactly what you ask for. They are a bit dated in certain regards, but also definitely more detailed than Morgan's work.