I just want to add that a reading of The Shell Game by Steve Alten gives a very digestible synopsis of the history and background of why it is that Professor Diamond's statement is so true:

There are 23 countries in the world that derive at least 60 percent of their exports from oil and gas and not a single one is a real democracy.

Alten gives a comprehensive overview of how the House of Saud came to power, and how they brutally loot their own country's oil resources for their lavish gain and the terrible destitution of their citizens (subjects, as they are). It's remarkable how fragile is their hold on Saudi Arabia, and much depends on how long the oil production holds out.

The book is a work of fiction, based on very detailed , accurate facts and research.  The fiction part is the extrapolation of all that factual research into the real problem facing all the nations of the earth:  the end of oil.  And how that bleak future may look by 2012.  

It's stunning to read all the disparate factors (such as all you stated in this diary), including the history of how the Sunnis and the Shia came to be like the Hatfields and McCoys; and how the US apparently plays all the oil-producing nations against each other in a game of political brinkmanship in the jostling to control the last reserves of oil on earth, all allegedly under the cover of "spreading democracy".

The shell Game is a useful adjunct to the information you've articulated in this diary.