Formerly independent nation, now contained within Ethiopia, comprised of an indigenous (and largely Islamic) African people called the Oromo.
In 1934, southern Oromia was subjugated by Ethiopian emperor Haile Selassie I, and has been occupied ever since. Revolutions and guerrilla warfare have frequently occurred as the Oromo demand self-determination, although the independence movement does not seem to have the same fervor as the recently successful Eritrean movement that created the nation of Eritrea from northern Ethiopia.
Look at http://www.oromoliberationfront.org for more details.