North Africa became completely integrated into the Mediterranean world. The East African coast was very important to the Indian Ocean network of exchange. The Northeast African kingdoms, Meroe and Axum, traded with Eurasia and this affected them culturally. One of the important culture changes was that they adopted Christianity and some later adopted Islam.
The Americas did not have large domestic animals (besides llamas and alpacas) and the could not adopt technologies and crops from Eurasia, which made them try to come up with their own.