Sectarianism in the Middle East has intensified since the U.S.-led invasion of Iraq and the outbreak of the Arab Spring, and has transformed into local sectarian and regional geopolitical confrontations among some Gulf States and Iran. The nature of this conflict is disputed. Is it a geopolitical regional rivalry or a purely sectarian conflict? This paper argues that it is a geo-sectarian contest over the Gulf. Therefore, firstly it argues that the nature of the conflict is fundamentally geopolitical. Secondly, it traces and analyzes the factors that led to the rise of sectarianism. Finally, it discusses the legitimacy of the emergence of a Sunni camp against the Shia camp.