There is no compelling evidence that such trans-Atlantic contacts took place and that there are no generally accepted artifacts of African provenance in the Americas. Scholarly consensus confines such hypotheses to the realm of pseudohistory.
A subset of broader claims of Pre-Columbian oceanic contact between the Americas and other parts of the world, these claims generally contend that one or more expeditions or migrations from Africa crossed the Atlantic to arrive somewhere in the Americas, where their African cultures combined with or influenced the indigenous pre-Columbian cultures. The proponents of these theories claim to detect evidence of this African cultural influence among a variety of artifacts, historical documents, native mythologies and supposed linguistic similarities.
Genetic and immunological studies over the past two decades have failed to yield evidence of precolumbian African contributions to populations in the Americas. Additionally, the huge mortality associated with the spread of Old World diseases introduced by Europeans suggests long-term immunological isolation.
Follow up tests by way of the hair shaft - performed to rule out contamination - offered the same results. The significance of these finds lie with the fact that both coca and tobacco plants are indigenous to the Americas and thought not to have reached Africa until after the voyage of Christopher Colombus, in 1492. Subsequent examination of numerous Sudanese mummies undertaken by Balabanova, mirrored what was found in the mummy of Henut Taui.
Balabanova suggested that the tobacco may be accounted for since it may have also been known in China and Europe, as indicated by analysis run on human remains from those respective regions. Balabanova proposed that such plants, native to the general area may have developed independently, but since have gone extinct. Other explanations were that of possible fraud or transportation of seeds by way of an African Swallow, with the former hypothesis being discarded by curator Dr. Alfred Grimm of The Egyptian Museum in Munich, after carefully reviewing the evidence. Sources of nicotine other than tobacco and sources of cocaine in the Old World are discussed by the British biologist Duncan Edlin in A look at the Evidence for Cocaine in Mummies
Most mainstream scholars remain skeptical, seeking more conventional explanations, while many alternative historians see this as proof of ancient contact between Africa and the Americas, well before Columbus.
The Olmec civilization of Central America, based along the Gulf Coast of south-central Mexico, existed roughly from 1200 to 400 BC. Some Olmec sculptures appear to represent faces with Negroid features. Seventeen monumental basalt stone heads, each weighing ten to forty tons, have been unearthed in Olmec sites along the Mexican Gulf Coast. José Melgar, who discovered the first colossal head at Hueyapan (now Tres Zapotes) in 1862, subsequently published two papers that attributed this head to a "Negro race". The great majority of scholars who specialize in Mesoamerican archaeology and history regard these speculations as incorrect.
Other claims have been made for certain types of bananas, cotton, beans and yams. However, these claims have been refuted by botanists. There were no bananas in the Americas prior to Columbus. The jack bean, which is claimed as an African introduction, is actually native to South America. The term "yam" is actually applied to two entirely unrelated plants, one of which is native to the Americas (the sweet potato), the other of which is native to Africa, and neither of which was found prior to Columbus in the other's continent. Finally, cotton includes a number of species, some of which are native to the Americas, others which are native to other parts of the world. There is no evidence at all of any African species of cotton in the Americas prior to Columbus. There is conclusive evidence, on the other hand, that the two principal native American species of cotton (Gossypium hirsutum and Gossypium barbadense) were cultivated by indigenous Americans long before any of the claimed contacts occurred.
According to van Sertima, evidence of a black presence in the America was given to Columbus by the natives, who allegedly indicated to the Spanish that they were trading with black people. His book claims Columbus later recorded that “The Indians of this Española said there had come to Española a black people who have the tops of their spears made of a metal which they called gua-nin". In his book, Columbus sent samples of this to Spain to have them examined, where it was later found that of 32 parts, 18 were of gold, 6 of silver and 8 of copper; similar in composition to comparable metals of West African origin.. However, alloys of gold, silver, and copper of a range of different proportions had been made in South America for 1400 years before the arrival of Columbus. Furthermore, Africans had been smelting iron and steel for well over a thousand years by this time. Van Sertima claims the origin of the word gua-nin can be traced to the Mande languages of West Africa. However, a term similar to "guanin" is also used in a number of Arawak languages to name this alloy.
Van Sertima claims that in 1513 Vasco Nunez de Balboa encountered a group of black war captives in an Indian settlement. The Indians are said to have told Balboa that they were at war with a nearby settlement of these "dark men". This was three years after the settlement of San Sebastian near the current Panama border and Santa Maria de la Antigua del Darien in Panama. According to Van Sertima, Friar Gregorio Garcia wrote an account of another encounter in a book suppressed by the Inquisition: “Here we found prisoners of war - Negroes - who were the first our people saw in the Indies.” What Van Sertima does not mention is that this would have been written in either 1607 or 1625, the dates of his two publications, generations after the first Africans were brought to the New World by the Spanish.
In his De Orbe Novo, Peter Martyr d'Anghiera mentions the presence of blacks in Panama. His theory is that these were “negro pirates of [Africa who] established themselves after the wreck of their ships in these mountains.”
In his book Massaalik al-absaar fi mamaalik al-amsaar (The pathway of sight in the provinces of the kingdoms), the historian Chihab ad-Dine Abu Abbas Ahmad bin Fadhl al-Umari (1300-1384) describes an expedition into the Atlantic. He relates a story obtained from the Mamluk governor of Cairo, Ibn Amir Hajib. While Mansa Musa was visiting Cairo as part of his pilgramate to Mecca, Ibn Amir Hajib asked how he had succeeded to the throne, and this is what Ibn Amir Hajib reported he was told:
A claim has been made that fleet landed in Brazil in around 1312, in the place now called Recife and that Pernambuco is allegedly an aberration of the Mande name for the rich gold fields of the Mali Empire.
However, no concrete evidence of any African artifacts, let alone the remains of even one of the 2,000 ships, has ever been found in the Americas.