In the wake of the 1979 Iranian revolution, relations between states in the Middle East were reconfigured and reassessed overnight. Amongst the most-affected was the relationship between Iran and Saudi Arabia. The existence of a new regime in Tehran led to increasingly vitriolic confrontations between these two states, often manifesting themselves in the conflicts across the region, such as those in Lebanon and Iraq, and more recently in Bahrain and Syria. In order to shed light upon this rivalry, Simon Mabon examines the different identity groups within Saudi Arabia and Iran (made up of various religions, ethnicities and tribal groupings), proposing that internal insecurity has an enormous impact on the wider ideological and geopolitical competition between the two. With analysis of this heated and often uneasy relationship and its impact on the wider Middle East, this book is vital for those researching international relations and diplomacy in the region.