http://www.bbc.co.uk/worldservice/africa/features/storyofafrica/2chapter5.shtml – BBC article about the Bantu migration in Africa, containing audio clips from various experts discussing the topic.
https://www.ancient.eu/Olmec_Civilization/ - Article from the Ancient Encyclopedia covering various dimensions of the Olmec civilization.
http://www.ohiohistorycentral.org/w/Hopewell_Culture – Ohio History Central gives an overview of the Hopewell culture in North America.
https://www.youtube.com/watch?v=Q6eBJjdca14 – What made the Mayans unique in comparison to other societies of the time? National Geographic expands on the Mayan people and their society.