At https://archaeologynewsnetwork.blogspot.co.uk/2017/01/ancient-figures-re… … Ghana had gold and slaves. It therefore became a magnet and attracted merchants from the other side of the Sahara. Whether this included traders in the Roman period or not it unclear but it certainly did in the Islamic ascendancy between the 6th and 13th centuries AD. As such, Ghana was keyed into a massive trade network from China and Indonesia to Spain, a network of trade routes. This has been demonstrated by a piece of archaeological science – looking at the residue of ancient plant material. They have found evidence of pines and bananas – and these did not grow in Africa south of the Sahara.
See also www.ghanaweb.com/GhanaHomePage/history/ancient_ghana.php .. and if this doesn't work try https://www.ancient.eu/Ghana/ … or www.ushistory.org/civ/7a.asp