Sounds interesting. More or less when is this suggested to have occurred? Also, would these blacks have been Asian Negritos or Africans, or no attempt to differentiate made to date? I remember seeing a cup in an Epcot display described as Central American, but it looked seriously Japanese to me. I also remember reading about linguistic traces around Peru similar to Central American tribal language, don’t ask me which or when. Today many underestimate the capacity of earlier man to travel.
And that, I think is the key. The Olmec giant heads for example, are negroid