When arriving or trying to arrive at a final agreement with neighbouring states over the status and alignment of international borders, many modern Middle Eastern states have been troubled by the unsatisfactory definition of original delimitations. These were drawn up typically at a much earlier stage by European colonial powers, or, as is the case in this chapter dealing with the Persian Qajar and Ottoman empires, by European imperial powers with a strong degree of leverage over the area. This is true of both inter-state land borders running overland and those running along rivers. The line of the Kuwait/Iraq boundary demarcated by a United Nations team as recently as November 1992 was essentially an interpretation of the vague and ambiguous wording of an Anglo-Ottoman territorial understanding that has survived to constitute the legal definition of this limit since 1913.1 Divided international rivers are rare in the Middle Eastern region, but the same problems of reconciling poor textual definitions to the physical features they supposedly describe have been experienced in all instances. If, as a result of the current "peace process", Israel ultimately arrives at final border settlements with its Arab neighbours, use will undoubtedly be made of the original definitions that introduced the territorial limits of mandated Palestine. With Jordan, eventual agreement on the boundary along the River Jordan will be based upon a vague stipulation of 1922 that the delimitation should run along the "centre" of that river.2 Fortunately, even by 1922, certain important ground rules had been established concerning where boundaries should run along international rivers. The Versailles treaties of 1919 prescribed that international boundaries running along navigable rivers should assume a thalweg delimitation, that is along the line of continuous deepest soundings.3 At the same time, a median line delimitation was deemed more suitable for non-navigable international rivers.