Each gada class remains in power during a specific term (gada) which begins and ends with a formal power transfer ceremony” (Herbert S Lewis,1994 ). Lewis brief the definition as “…a group of men, ideally of about the same age who are initiated together, pass through a series of grades, and when their time comes they take over the governing of their people for an eight year period. They elect officers among themselves, and administer the people, but they must also satisfy and convince the assembly of the whole people to whom they are ultimately responsible”. The value system of Oromo society has been influenced by the “Gadaa” and “Siiqqee” institutions.
But, the Oromo people passed through different types of colonial experience under the Ethiopian ruling class. Mohammed Hassen, in a JOS (1999) discussed an Oromo colonial experience by dividing into different stages. Hassen asserted that, first, it is not easy to present the Oromo colonial experience from the 1870s to I990s in an article of appropriate length for a single journal volume. After the conquests, the Oromo institutions of self-government (including the Chafee assembly or parliament) were abolished. The indigenous leadership was liquidated or co-opted, the land confiscated, and cultural institutions destroyed. The conquerors banned religious pilgrimages to the land of “Abbaa Muudaa” and looted the property of both the settled and the pastoral communities (Mohammed Hassen).