The study examines causes of the Middle-Belt movement and its identity In Northern Nigeria. It relates this identity to Nigerian Politics and Federation. The study suggests that internal colonialism of the Islamic society on the M-Belt groups were contributive to activating minorities identities and the organization of the M-Belt movement. The roots of internal colonial relationships were from a colonial system which the British incorporated with the M-Belt groups in 1900. In the processes of Incorporation before 1940, British adminstration subordinated many M-Belt groups to Islamic leadership. The M-Belt movement was a reaction to colonial relationships and domination by cultural ly different groups. The reaction took the form of activating tribal support for creation of a M-Belt Region. This was meant to separate the M-Belt and the Islamic society into different units of the Federation. Tribal identities developed from chieftancy institutions among some of the fl-Belt groups were reinforced by modernization, with European Missionaries dominating the processes and produced Christian political leadership. The tribal identities, were complemented by a trans-tribal Christian religious identity, to produce cohesion and collective political demands. Variation in processes of modernization between the Islamic society and M-Belt groups in a North, under Islamic leadership, conditioned support of non-Islamic groups for the M-Belt movement. The combination of these factors and with the North as an outsized unit, produced conceptions of regionalism. The thesis studies the futherance of their cause in the development of Middle-Belt political parties and the UMBC party under the leadership of J. S. Tarka. While the causes for the regionalism resulted into re-structuring of Nigeria in 1967 in which Benue-Plateau State emerged and enclosed prominent minorities in the M-Belt Movement, sub-regionalism produced localism.Although localism in the political identity of M-Belt groups, destroyed conceptions of the M-Belt, its religious identity remains powerful in Nigerian Politics