African classical music, what little I've heard, tends to be as interesting as any nationalistic classical music, especially when the language of Western music is combined with the folk tunes and indigenous rhythms of the homeland. This is yet another area of classical music about which I know very little and wish I knew more; there's a blog called AfriClassical that explores this area. African influence on music is, I suppose, often thought to be strongest through the importation of native rhythms and song to the Americas through the slave trade and then eventually into jazz, but it's only natural that a classical tradition should spring up as the cultural pollination started going the other way, as well.
For a 'U' composer, I found Joshua Uzoigwe. Biographical information on Uzoigwe seems a bit scant, but he lived from 1946 to 2005 and was a native of Nigeria. This work of his, called "Ukom (from 'Talking Drums')", is a very pleasurable study in rhythm.