‘Allegedly’

>The explanation favored by Sagan is that the Dogon were visited by a technological civilization, but not an extraterrestrial one. The nature of the knowledge imparted is consistent with a visit by a science attentive person in the 1930s or 1940s when the discovery of the nature of Sirius B was being widely discussed in popular science books. This information could then have been woven into the Dogon's existing mythology in time to give Griaule and Dieterlen something very interesting to write home about.

>A variation on this theme is that the knowledgeable visitor and the source of the information might have been Griaule himself. Though an anthropologist, Griaule had studied astronomy in Paris. He was aware of the discovery of Sirius B and may have over interpreted the Dogon responses to his questions.

>In 1991 Walter van Beek, a Belgian anthropologist, led a team of anthropologists to study the Dogon tribe. Although he hoped to find evidence for their astounding astronomical knowledge, the team found no trace of the detailed Sirius lore reported by Griaule.

https://chandra.harvard.edu/chronicle/0400/sirius_part2.html