Ancestry of medieval Swahili people revealed in genetic study

Medieval people living on the ‘Swahili coast’ – the Indian Ocean coast of eastern Africa – have African and Asian ancestry according to new research on ancient DNA.

An international team of researchers, including people from the United States, Great Britain and Kenya, Archaeologists believe that the results confirm that relationships between Asian merchants and African traders were formed between the years 900 and 1100 in coastal towns in Kenya and Tanzania.


The research, published last month in Nature, included the newly sequenced ancient DNA of 80 individuals from the Swahili coast and inland neighbours dating from 1300 CE to 1900 CE. They also included new genomic sequences from 93 present-day Swahili speakers and previously published genetic data from a variety of ancient and present-day eastern African and Eurasian groups.

The DNA information was analyzed at the Reich Laboratory at Harvard University. It showed that people of African and Persian descent began to have children together around the turn of the second millennium. The descendants of those children dominated Swahili towns 500 years later and were recovered from the burial sites excavated by the team.


“We have long believed that cultural changes were associated with the adoption of Islam and this new research gives us a genetic timeframe that suggests that this is a reasonable assumption to make,” explains Stephanie Wynne-Jones from the University of York. “Merchants from Persia travelled to the African coast for trade, and would have stayed for long periods of time. DNA from the burial sites we have been studying shows African and Persian ancestry. The Persian line came from men, suggesting they were forming relationships with African women.”

Analyses also showed that the initial stream of migrants had about 90 percent ancestry from Persian men and 10 percent ancestry from Indian women. Although South Asian-associated artifacts are well documented at Swahili archaeological sites and Indian words have been integrated into Swahili, “no one had previously hypothesized an important role for Indian people in contributing to the populations of the medieval Swahili towns,” said David Reich, professor of genetics at the Univeristy of Harvard.

Jeffrey Fleisher, from Rice University, and one co-author of the study, said: “Oral histories of the Swahili who live in East Africa have often told us of their Persian ancestry, which for many years researchers have believed was a way for the Swahili people to use their Persian and other foreign trade links for political gain, but our data reveals that these oral records were correct, showing how important it is to take oral traditions seriously.”

One of the sites excavated along the coastline. Photo courtesy University of York

After about 1500 CE, ancestry sources became increasingly Arabian. In later centuries, intermingling with other populations from Asia and Africa further changed the genetic makeup of Swahili-coast communities.


The study confirmed that the bedrock of Swahili culture remained unchanged even as the newcomers arrived and Islam became a dominant regional religion. For example, the primary language, tomb architecture, cuisine, material culture, and matrilocal marriage residence and matriarchal kinship remained African and Bantu in nature.

The findings contradict one widely discussed scholarly view, which held that there was little contribution from foreigners to Swahili peoples, the authors said. The researchers added that the findings also refute a diametrically opposed viewpoint prevalent in colonial times, which held that Africans provided little contribution to the Swahili towns.

The researchers also noted that the findings align with the oldest Swahili oral stories, which tell of Persian (Shirazi) merchants or princes arriving on the Swahili shores. “It was exciting to find biological evidence that Swahili oral history probably depicts Swahili genetic ancestry as well as cultural legacy,” said Esther Brielle, research fellow in genetics in the Reich lab.


“This data must be seen as a catalyst for a new, less binary, approach to Swahili society,” Professor Wynne-Jones adds. “It shows that people were moving and establishing deep connections and families in the Indian Ocean region, and that Persian migrants would have been part of the cosmopolitan world created by coastal African societies. The research that has underpinned this study is part of a long-term commitment to exploring human experience and daily life on the coast.”

The article, “Entwined African and Asian genetic roots of medieval peoples of the Swahili coast,” by Esther S. Brielle,  Jeffrey Fleisher, Stephanie Wynne-Jones et al., appears in Nature. Click here to read it.