According to the latest 2007 national census, Islam is the second most widely practised religion in Ethiopia after Christianity, with over 25 million (or 33.9%) of Ethiopians adhering to Islam according to the 2007 national census, having arrived in Ethiopia in 615. Islam is the religion of the overwhelming majority of the Somali, Afar, Argobba and Harari, and the largest group of the Oromo peoples of Ethiopia according to the 1994 national census.
- "Census 2007", first draft, Table 6. The total population size for this Region includes 8 rural kebeles in Elidar woreda, whose numbers were estimated. The statistics in the latest version of the CIA World Factbook are taken from the 1994 national census.
- J. Spencer Trimingham. 1952. Islam in Ethiopia. Oxford: Geoffrey Cumberlege for the University Press, p. 44