Complex sentence: The Luba people consist of many sub-groups with distinct Luba language dialects, of which three are main: the Luba-Kasai, Luba-Katanga, and Swahili languages.
Split into simpler sentences: The Luba people consist of many sub-groups with distinct Luba language dialects. The three main dialects were: the Luba-Kasai, Luba-Katanga, and Swahili languages.