Egypt's Nile Delta region is wide and flat, and eons of seasonal flooding have left it with deep layers of fertile sediment. The delta's compact shape also allows for some economies of scale in infrastructure development. But perhaps most important, the delta allows for contact with the outside world. Egypt is extremely capital poor and gaining even indirect access to global capital markets is no small achievement. Extending Egyptian influence downstream to the Mediterranean is absolutely critical. The opposite is true when Egypt pushes upstream, where it quickly encounters diminishing returns. The Nile River Valley narrows the farther south it goes, increasing the relative costs of development. The valley does widen eventually, but by the time it reaches Khartoum, Egypt finds the area impossible to control. That far south, rainfall finally increases to the point that populations can exist beyond the river. This places Egypt in competition for the river's water resources while robbing it of the insulation of the deserts. In addition, Khartoum is fully 1,600 kilometers (994 miles) from Aswan and 2,600 kilometers from Cairo. The supply chains necessary to occupy these far southern regions are at the extreme upper limit of what Egypt can sustain, and it can do that only when Egypt is powerful and its southern neighbors are weak. Such a balance of forces in the south is not the situation today. In modern times, Egyptian power stops at the northern shore of Lake Nasser. The creation of the Aswan High Dam flooded the Nile valley south to and beyond the Sudanese border, drowning all connecting infrastructure with it. At present, there are no significant infrastructure links between Egypt and Sudan.
