Search

At the dawn of the second millennium, the expansion of the Indian Ocean trading network aligned with the emergence of an outward-oriented community along the East African coast to create a cosmopolitan cultural and trading zone known as the Swahili Corridor. On the basis of analyses of new genome-wide genotyping data and uniparental data in 276 individuals from coastal Kenya and the Comoros islands, along with large-scale genetic datasets from the Indian Ocean rim, we reconstruct historical population dynamics to show that the Swahili Corridor is largely an eastern Bantu genetic continuum. Limited gene flows from the Middle East can be seen in Swahili and Comorian populations at dates corresponding to historically documented contacts. However, the main admixture event in southern insular populations, particularly Comorian and Malagasy groups, occurred with individuals from Island Southeast Asia as early as the 8th century, reflecting an earlier dispersal from this region. Remarkably, our results support recent archaeological and linguistic evidence-based suggestions that the Comoros archipelago was the earliest location of contact between Austronesian and African populations in the Swahili Corridor. We acknowledge support from the GenoToul bioinformatics facility of Genopole Toulouse Midi-Pyre´ne´es, France. This research was supported by French Ministry of Research grant ANR-14-CE31-0013-01 (OCEOADAPTO) to F.-X.R, a Rutherford Fellowship from the Royal Society of New Zealand (RDF-10- MAU-001), a fellowship from the Alexander von Humboldt Foundation to M.P.C., and grants from COMPETE 2020 and a Fundac¸a˜o para a Cieˆncia e a Tecnologia-funded project (POCI-01-0145-FEDER-016609) to V.F. We thank Kamil Merito for his help collecting East African samples. We thank all the local Swahili and Comorian communities who participated in this study.