most beautiful valleys in the world

The 6,650 km long Nile River is generally considered the longest river, and it flows through ten countries including: Sudan, South Sudan, Burundi, Rawanda, Congo, Tanzania, Kenya, Ethiopia, Uganda, and Egypt. The ancient Egyptian civilization depended upon this river. Most of the population is concentrated alongside the river, and almost all of the historical archaeological sites are located along the river bank. The River Nile floods annually and leaves behind a lot of fertile clay after receding, and this results in bumper crops. It was customary during ancient times to offer human sacrifices to the river. After the construction of the Aswan Dam in 1970, there is no annual flooding of the river.