Mali does really get it rough. The history of West Africa is actually very fascinating, but even with some cursory knowledge of the region,
they don't exactly possess mainstream/pop-culture appeal, historical appeal or any sort of deeply ingrained fearsome reputation that many of the others do.
The only thing analytically speaking that they have going for them at the moment is hipster appeal.
Kongo at least has Msiri who was a realpolitik and geopolitical genius, who was cut short because the deck was already stacked against him
and Ethiopia has several things going for it as well, but Mali...
we just have Mansa Musa the tech whore (who admittedly makes a great vassal in vanilla BtS due to how easily he vassalizes)
gameplay wise and low awareness of West African history and culture.
Phoenicia.