Geographically, the Nubian region can be called the corridor to Africa, linking sub-Saharan Africa and Egypt. As a narrow ribbon of the fertile Nile-Valley it stretches between the first cataract at Aswan and the fourth cataract near al-Debba. The more than 900 km long stretch was divided into Lower Nubia (between the first cataract and the second cataract near Wadi Halfa) and Upper Nubia (from the second cataract southwards). Following the final suppression of the Mahdi uprising in the Sudan (1898), the British government decided that latitude 22 degrees north would be the political boundary between Egypt and the Anglo-Egyptian Sudan. And thus Nubia came to be divided arbitrarily.