Like many, I followed the Arab Spring protests of 2011, which toppled dictators in Tunisia, Egypt, Libya, and Yemen. However, not only was I unaware of the impact of the Arab Spring on the Gulf monarchies of Saudi Arabia, Bahrain, Kuwait, Oman, Qatar, and the United Arab Emirates, but I have to confess I didn't know very much about these countries in general. Sectarian Gulf provided a useful introduction to the modern political history of the Gulf nations, focusing on the Arab Spring and its aftermath.
Matthiesen's thesis is that the ruling families, "above all, the Bahraini and Saudi ruling families, have played on and strengthened sectarian divisions between Sunni and Shia to prevent a cross-sectarian opposition front", which, with "old tactics of denial, repression, economic largesse, and defamation" helped them maintain power for now. He concludes that it is only going to grow more challenging for them as their citizens demand greater democracy, more equitable distribution of resources, and the rule of law, in a future in which domestic demand for oil increases as reserves and export revenues decline in the next few decades. He buttresses his case with prodigious research (the 192-page book includes 50 pages of footnotes) and anecdotes from his travels in the Gulf during and after the Arab Spring.
It wasn't an easy read for me, because it was hard to keep track of the complicated dynamics among a great many political factions and Islamic sects both within the Gulf itself and elsewhere, and because of my unfamiliarity with the many Arabic names of people and organizations, but I learned quite a bit.