The Bamana (Bambara) tonal system is characterized by two levels with a downdrift and downstep; low tone is the marked one; the tonal compactness rule regulates a merger of adjacent tonal domains within syntactic groups of certain types; a floating low tone plays a role of a definite/referential article. Dan Gwɛɛtaa has 5 level tones; context changes of tones are quasi-nonexistent; there are numerous grammatical tonal modifications; in the majority of cases, it is the extralow which appears as a grammatical tone; an interpretation of extralow as a default tone can be suggested. Although both languages belong to one mid-range family, the tonal systems of Bamana and Dan-Gwɛɛtaa seem totally different. There are two factors that can explain this divergence. The first one is just the time distance: as is proved by the history of better documented languages (especially those of East Asia), 4000 years (and even less) of independent evolution is quite enough to let tonal systems transform radically. The second factor is the areal influence: among all South Mande languages, Dan seems to be the most influenced by Kru languages whose typical characteristics are the polytony and multiple grammatical tones. Bamana (and other languages of the Manding group), to the contrary, has a long history of contacts with non-tonal languages (Pulaar-Fulfulde, Wolof) or two-tone languages which tend to evolve towards accent-like systems. This environment was less conductive to the complication of its tonal system and grows of the functional load of tones.