Nilo-Saharan languages refer to a group of languages found in Sub-Saharan Africa, primarily in the Sahel region. The term Nilo-Saharan was coined by the German linguist Carl Meinhof in 1911 and has since been widely used to describe this language family. Other synonyms for Nilo-Saharan include the Saharan family, the Nilotic languages, or the Nilo-Saharan phylum. The Nilo-Saharan language family includes around 200 languages spoken by diverse ethnic groups such as the Dinka, Zande, Kanuri, and Luo. Nilo-Saharan languages are known for their complex grammatical systems and the use of tone and vowel length.