I'm not agreeing with Henri about adding a small Brazilian rogue state as a civ, but he is right that Angolans and Congolese were a major component of the quilombos. Even at the time plantation owners asked slavers to stop buying slaves from Angola and Kongo because they were more warlike and less submissive than other slaves. I think some reference to quilombos in Civ7's Brazil would make sense, since there will never be a Palmares civ.