[AlexBrith]

African civilizations were largely unknown and had no real impact upon any other people. By the time Euros began colonizing Africa seriously those "empires" were already gone and their material legacy was rather scarce.
In case of Mesoamerica Euros had to face strong opposition from a relatively sophisticated civilization that has left numerous architectural sites as its legacy.

If that makes you feel more comfortable Georgians also never made it into AoE and the like narrative despite having quite developed states in antiquity. I guess you just need to accept the unpopularity of Black civilizations among other people or try to promote those cultures without usual silly Afrocentrist claims.