Senegal is subdivided into 14 regions (French: régions, singular – région), each of which is administered by a Conseil Régional (pl.: Conseils Régionaux) elected by population weight at the arrondissement level. Senegal is further subdivided into 45 departments, 103 arrondissements (neither of which have administrative function) and by collectivités locales (the 14 regions, 110 communes, and 320 communautés rurales) which elect administrative officers. Three of these regions were created on 10 September 2008, when Kaffrine Region was split from Kaolack, Kédougou region was split from Tambacounda, and Sédhiou region was split from Kolda.
To date, all regions take their name from their regional capitals.
More information on the Wikipedia page [1].