The same can be said about many Arab nations who were not countries, but various Arab tribes living in the same regions who would at times fight each other. Yet, look at the Khaleej now? Tribal and poor desert dwellers have managed to put their disputes aside and get on with it.
That is just an excuse we tell ourselves to hide from the stark reality that we are indeed the only homogeneous SSA country. We share the same heritage, language, culture and religion. Countries for the most part are colonial artificial concepts in which people from different ethnic groups who speak different languages have been forced to share borders, yet Somalis in Somalia have been delt a good hand and still can't make it work.