This paper argues that colonialism bred the phenomenon of ethnic disintegration among the Mbum leading to mutual suspicion among the various clans. The Mbum constitutes one of the major ethnic identities of the Bamenda Grassland of Cameroon. Historical narratives aver that the people claim disparate origins and migration in three identifiable groups including the Warr, the Yaa and the Tang Clans. Upon their settlement in the Nkambe Plateau, geography, history and culture conspired to knit them together into an ethnic identity. However, colonial encounter with the Germans in 1902 and the British in 1916 led to the implementation of policies that estranged this ethnic identity causing disintegration. Notably, the German divide-and-rule policy sowed the seed for disintegration while the British reorganization of 1935 re-emphasized the Clan lines which forced the people to retrocede into perpetual disintegration. The three Clans became particularistic and attached to individual Warr, Yaa and Tang Clan identities making ethnic unity among the Mbum a misapprehension. This situation created a situation where Clan nationalism superseded ethnic cohesion as manifested during the period of party politics in the area with far reaching attendant repercussions. The paper also provides a microcosm for the appreciation of the degree to which colonial rule and strong attachment to individual national pride has ultimately cost Africa the much cherished unity. Oral, archival as well as written documents were used to defend its thesis.