The Nilotic peoples take their name from the Nile and their definition from a branch of the Nilo-Saharan language family. They include the Dinka and Nuer of South Sudan, the Shilluk of the White Nile, the Luo of Kenya, Uganda and Tanzania, and the Maasai, Samburu, Turkana and Karamojong of the East African rift. Between them they range from the cattle camps of the Sudd wetlands to the open savannah, and they have never formed a common polity or used a common name for themselves. What they share is descent of speech, and the atlas says so on the row rather than letting a reader infer more.
The grouping is also the source of a substantial body of anthropology: E. E. Evans-Pritchard's work on the Nuer in the 1930s and 1940s became a foundational text for the discipline, and the Dinka and Nuer accounts of divinity that came out of that tradition of fieldwork, above all Godfrey Lienhardt's, are among the most cited descriptions of any African religion. That prominence is a fact about who did fieldwork where, and not a measure of how important these traditions are relative to others. The peoples covered are also divided by the borders drawn over them. The Luo are split between three countries, the Maasai between two, and South Sudan's Dinka and Nuer have been on opposite sides of a civil war whose reporting frequently mistook a political conflict for an ethnic one.
Sources The Nuer: A Description of the Modes of Livelihood and Political Institutions of a Nilotic PeopleE. E. Evans-Pritchard with Divinity and Experience: The Religion of the DinkaGodfrey Lienhardt, Sudan's Prolonged Second Civil War and the Militarization of Nuer and Dinka Ethnic IdentitiesJok Madut Jok and Sharon E. Hutchinson