No account of Sirius is complete without the Dogon material, and it is a case where the evidence has moved decisively and the popular version has not.
The claim is that the Dogon people of Mali possessed, before contact with modern astronomy, knowledge of Sirius B, that it is small, extremely heavy, and orbits Sirius in about fifty years. The source is the French anthropologists Marcel Griaule and Germaine Dieterlen, whose fieldwork from the 1930s onward reported a Dogon cosmology including a companion star called po tolo, made of the heaviest substance and circling Sirius over roughly fifty years. Robert Temple's The Sirius Mystery of 1976 turned this into an argument for extraterrestrial contact, and it has circulated ever since.
The scholarly position has shifted substantially against it. The anthropologist Walter van Beek conducted extended fieldwork among the Dogon in the 1980s and reported that he could not find the Sirius knowledge Griaule described, that informants did not recognise it, that the star-related material was neither secret nor systematic in the way reported, and that Griaule appeared to have shaped his findings through his own questioning. Griaule's methods have been criticised more broadly for producing an unusually coherent cosmology through leading interviews with a small number of informants.
There is also a straightforward contamination route. Sirius B was discovered in 1862, its density established in the 1910s, and its orbital period was in the popular literature well before Griaule arrived; French colonial schools and missionaries were present in the region.
The honest summary: the ethnography is contested, the transmission route is available, and the extraterrestrial reading has no support beyond the disputed ethnography.