By lumping together such a hugely diverse group of countries without any seemingly connecting geographical characteristics actually works to deepen those divisions and highlight the cultural differences between the many, many different peoples pf the region.

This is the main idea. The empires of the middle ages have now been turned into nations with their own political, religious, and cultural backgrounds that continue to diminish the connections in the region, thus making a "unified" MIddle East less probable if not really an unrealistic and problematic idea.

Did the "abode of Islam" not fit in with the idea of nation states and the growing number of secular empires that were emerging in the geographical region now known as the "Middle East"? Possibly, the European map makers and political leaders of the time did not like the idea of a growing and prosperous "abode of Islam". Especially since the European churches had undergone a lot of recent reforms and schisms during that time.

How have these borders grown?

The "west" as self and the "east" as other has deep roots. This seems to be the crux of the European centric dichotomy.

Ottoman, Mughal, Sagavid, and Uzbek empires emerged as independent states. The author then notes that these empires were not in a larger "Islam" state but rather politically and culturally unique.

Main Idea-There is not a single middle eastern identify or unifying characteristic that ties together the countries of this region. Rather, they are diverse in regards to ethnicity, geography, religion, and nationalities.