On the eve of World War I Britain and the Ottoman Empire reached an agreement on their respective spheres of interest in Arabia, drawing boundaries known as the Blue and Violet lines. Based on political convenience and bad law, the Blue and Violet lines have been a constant source of legal disputes between Saudi Arabia and its neighbours. This book looks at the history of boundary drawing between these states in the light of the geo-political structure of Arabia, concepts of territory and criteria for sovereignty, and the appropriateness of international law for solving the problems of drawing boundaries in the desert.