East Dangla and West Dangla, two dialects of the Dangla language which belongs to the Chadic language family, differ substantially in their tone systems. In numerous lexical items, entire or partial tonal inversions are observable. Earlier research has not succeeded in boiling this down to regular sound correspondences. In the meantime, data from Central Dangla as a third dialect have become available, which provide important insights into the matter. Based on all available materials, a new attempt to establish the tonal correspondences is undertaken here. This results in a reconstruction of the tone system of Proto-Dangla, the hypothetical ancestor of the modern varieties, together with a chronological elaboration of the tonal changes that occurred in the individual dialects.