The study deals with ethnic conflicts in the Guji and Borana Zones of Oromia NationalrnRegional State located at the southern pastoral low land of Ethiopia. Ethnic conflict isrninevitable in any community with diversified or the same culture, language andrnpsychological makeup. Two zones inhabited multi-ethnic pastoral communities whornoften face spasmodic challenges and regular threats as a result of ethnic conflicts in thernareas for a long period of time. The study addressed the inter and /or intra ethnicrnconflicts among the Guji, Borana, Gabra and Garri which are some of the violent ethnicrnconflicts in the study areas that could be described along ethnic lines. The main objectivernwas to investigate, describe, and analyse the major common and newly prevailing causesrnof the ethnic conflicts, impacts of ethnic conflicts and management mechanisms amongrnthem. Data was collected from both primary and secondary sources.Purposive andrnsnowball (non-probable) sampling techniques were used to gather genuinerninformation.To attain the study objective, qualitative method of data analysis wasrnemployed because it enables detailed study of social phenomenon based on feelings,rnexperiences, motives and behaviours of targeted groupâ€™s and the reasons that govern suchrnbehaviours of people.rnThough many ethnic conflict analysts, scholars, government, and non-governmentalrninstitutions took for grant that the causes of different violent ethnic conflicts recurring inrnthe pastoralist communities resulted solely as competition for resources (pasture land andrnscarcity of water). But the findings of this study showed that ethnic conflicts in the studyrnareas were initially, started by sense of traditional enemity, social recognition (killing forrnbraveness and pristige), resources, weapons effect and divide and rule, power dominancernand political manipulations were the common causes of the pre 1991 ethnic conflictsrnwhile newly prevailing causes of the ethnic conflicts are advanced to claiming for thernlocal identity, self-administration (governance), territorial expansion and local politicalrndemarcation which was/is granted by 1995 constitution because it created the sense ofrnlocal identity through ethnic based and political self-consciousness. The study consideredrnhighly interwoven intricate factors of historical, cultural, economic, political, and localrnidentity issues pertinent to the new federal model and the former groupâ€™s relations. Bothrnformal and informal ethnic conflict mechanisms are utilized and used to manage ethnicrnconflicts in bringing peace and social cohesion in the study areas but attempt made byrnformal institution is less effective than the one made by Jaarsummaa (indigenousrnmechanism) in establishing the lasting sustainable peace, social relation, andrnharmonization among the conflicting ethnic groups (Guji, Borana, Gabra and Garri).rnFailure in making harmony is due to lack of genuinity in implementation and Shadowrnplay by both local government and elites.