Intermarriage Shapes Ancestry: Ahom People Assimilate Genetically with Local Populations in Assam

A recent research found that the Ahom people of Assam, who have long been recognized as descended from migrants from Thailand, had heavily mixed with local populations, almost completely erasing their ancestral Southeast Asian genetic markers.

In comparison, Parsis and Jews in India have managed to hold onto their West Asian heritage. Within the last two millennia, all three groups have migrated onto the subcontinent.

According to Gyaneshwer Chaubey, a professor and population geneticist at Banaras Hindu University who has undertaken research on the genetic composition and demographic history of all three tribes, "Parsis and Jews have preserved their homeland signatures — not the Ahoms."

According to historical records, the Ahoms, also known as Tai-Ahoms, traveled around 800 years ago from Thailand and upper Burma (now Myanmar) to India. They founded a dynasty that ruled over modern-day Assam from AD 1228 to AD 1826, or about 600 years.

Research conducted in the 1970s using blood group studies suggested that the Ahoms may have originated in Southeast Asia. A preliminary analysis of the DNA of 22 surviving Tai-Ahom royal ancestors five years ago revealed affinities with contemporary Thai people.

Chaubey and associates conducted a more thorough analysis of the Ahom people's genetic composition in this research than they have in the past. In northeastern India, they found evidence that they believe suggests a small-scale migration followed by extensive intermarriage with the progenitors of the current local inhabitants.

"A study accepted for publication in the peer-reviewed scientific journal, Human Molecular Genetics, suggests a biological phenomenon where a small ancestral population loses most of (its) homeland ancestry due to excessive admixture with the locals," the researchers said in their accepted paper.

The Khasis, Kusundas, and Nyishis are the populations closest to the modern Ahoms, according to the research. The Kusundas share genetic ancestry with the Khasis but are linguistically connected to Nepal; the Nyishis are an ethnic Tibeto-Burman group with South Asian heritage; and the Khasis are an Australoasiatic demographic group having genetic ancestry from Southeast Asia and South Asia.

Today The majority of Khasis reside in Kusundas, Nepal; Nyishis, Arunachal Pradesh; and Meghalaya.

The dominant pattern of the Khasi, Kusunda, and Nyishi signatures in the Ahom, according to Chaubey, "suggests excessive admixture with an even earlier common ancestral population from which these three distinct population groups emerged."

Chaubey (2016) corroborated historical reports by demonstrating, using a comparable population genetics analysis, that the Jews of modern-day India are descended from individuals who migrated in Cochin (Kochi) from West Asia in the fifth century.

According to a 2017 research on the origins of the Parsi people in India, they are genetically closest to modern Iranians, confirming historical claims of Parsis migration to South Asia in the 7th century via DNA analysis once again.

Chaubey said, "But endogamy was practiced by Jews and Parsis, as well as by many other modern population groups across the nation." "There is no evidence that the ancestors of today's Ahoms were endogamy."

The study's co-leader was Niraj Rai, an expert in archaeogenetics at the Birbal Sahni Institute of Palaeosciences in Lucknow. The Deccan College in Pune, the Archaeological Survey of India, and Mangalore University were the other contributors.