1. The locality of the present dispute is the territory bordering the Bahr el Arab.  This 450-mile-long (720 km) river arises in south-western Sudan, then flows north-east, then generally south-east until it reaches the river Bahr el Ghazal, itself a tributary of the White Nile.  The course of the Bahr el Arab and other western rivers and streams is shown on the fold-out map (Figure 1) opposite the Table of Contents.  Seasonal streams such as the Ragaba ez Zarga may be dry for half the year; by contrast, the Bahr el Arab is a source of water and pasture throughout the year.