The Origin of the Bangla People (Bangladesh): An Integrative Population Genomics Perspective

Abstract The Bangla (Bengali) people of Bangladesh constitute one of the largest ethno-linguistic populations in the world, with a complex genetic history shaped by ancient South Asian ancestry, Indo-Aryan expansions, and regional admixture with East and Southeast Asian populations. Located in the fertile Ganges–Brahmaputra delta, Bengal has been continuously inhabited since prehistoric times and has served as a major corridor for human migration, trade, and cultural exchange. Population genomic studies using autosomal DNA, Y-chromosome markers, mitochondrial DNA (mtDNA), and ancient DNA (aDNA) reveal that modern Bangla populations derive the majority of their ancestry from ancient South Asian (Ancestral South Indian–related and Indus-derived) populations, combined with Indo-Aryan Steppe-related ancestry and a significant East Asian component. This review integrates genetic, archaeological, and linguistic evidence to elucidate the origins of the Bangla people and highlights how geography and history shaped their distinctive genetic profile within South Asia. 1. Introduction The Bangla people, commonly referred to as Bengalis, are the primary ethnic group of Bangladesh and also inhabit eastern India (West Bengal and Tripura). Linguistically, Bangla belongs to the Indo-Aryan branch of the Indo-European language family. Historically, Bengal has been a center of agriculture, urbanization, and cultural development for over four millennia. The genetic origins of the Bangla people cannot be explained by a single migration event. Instead, their ancestry reflects multiple demographic layers, including indigenous South Asian populations, Indo-Aryan expansions from the northwest, and gene flow from East and Southeast Asia. Advances in population genomics provide a powerful framework for reconstructing this complex population history. 2. Geographic and Historical Background Bangladesh lies in the eastern part of the Indian subcontinent, dominated by the Ganges–Brahmaputra–Meghna river system. This region has historically attracted settlers due to its fertile land and strategic position connecting South Asia with Southeast Asia. Key historical phases influencing Bangla genetic formation include: Paleolithic and Mesolithic settlement of South Asia Neolithic agricultural development in eastern India and Bengal Bronze Age Indus-related and Gangetic populations Indo-Aryan migrations during the late Bronze and early Iron Ages Historical interactions with Tibeto-Burman and Southeast Asian groups These events collectively shaped the genetic landscape of Bengal. 3. Genetic Methodologies Used in Bangla Population Studies 3.1 Autosomal DNA Analysis Autosomal DNA provides a genome-wide view of ancestry. Large-scale genomic studies of South Asian populations show that Bengalis cluster within the broader South Asian genetic cline but are shifted toward East Asian populations compared to northwestern Indo-Aryan groups (Reich et al., 2009). Bangla autosomal ancestry typically includes: Ancient South Asian ancestry (related to Indus Valley and pre-Indus populations) Steppe-related Indo-Aryan ancestry East Asian / Southeast Asian ancestry, higher than in most other Indo-Aryan speakers This East Asian component distinguishes Bangla populations from many other Indo-Aryan groups. 3.2 Y-Chromosome Analysis (Paternal Lineages) Y-chromosome studies reveal the following major haplogroups among Bangla males: R1a-Z93 – associated with Indo-Aryan and Indo-Iranian expansions H – linked to ancient South Asian populations O – associated with East and Southeast Asian ancestry J2 and L – reflecting West Asian and Indus-related ancestry The presence of haplogroup O at notable frequencies supports historical and prehistoric gene flow from East and Southeast Asia into Bengal (Sengupta et al., 2006). 3.3 Mitochondrial DNA (Maternal Lineages) mtDNA analyses show that Bangla maternal lineages are predominantly South Asian, with common haplogroups including M, R, U, and D. East Asian-associated mtDNA haplogroups (such as D and G) occur at higher frequencies in Bengalis than in northwestern Indian populations (Metspalu et al., 2004). This pattern suggests sustained maternal gene flow from eastern populations into Bengal. 4. Ancient Genetic Foundations of the Bangla People 4.1 Indigenous South Asian Ancestry Ancient DNA studies indicate that South Asian populations descend largely from a mixture of deeply rooted hunter-gatherer groups and populations related to the Indus Valley Civilization (IVC). This ancestry forms the genetic foundation of modern Bengalis (Shinde et al., 2019). 4.2 Indo-Aryan (Steppe-Related) Contributions During the late Bronze Age, populations carrying Steppe-related ancestry entered the Indian subcontinent from the northwest. This ancestry is associated with the spread of Indo-Aryan languages and is present in Bangla populations, though generally at lower levels than in northern Indian groups (Narasimhan et al., 2019). 5. East and Southeast Asian Gene Flow One of the most distinctive features of Bangla population genetics is the presence of East Asian ancestry. This component likely entered Bengal through: Migration of Tibeto-Burman-speaking populations Long-term contact with Southeast Asia via riverine and coastal routes Assimilation of indigenous eastern populations Genomic studies consistently show that Bengalis have higher East Asian admixture than most Indo-Aryan populations, reflecting Bengal’s role as a transitional zone between South and Southeast Asia. 6. Cultural and Social Structure and Genetics Historically, Bengal society was shaped by agriculture, urbanization, and relative openness compared to more arid regions of South Asia. While caste and endogamy existed, they were often less rigid than in northwestern India, facilitating gene flow among groups. This relative openness contributed to the genetic heterogeneity observed among Bangla populations today. 7. Medical and Evolutionary Implications Understanding the genetic structure of Bangla populations is important for medical genetics, particularly for studying metabolic disorders, infectious disease susceptibility, and population-specific genetic variants. The unique blend of South Asian and East Asian ancestry may influence disease risk profiles and drug responses. 8. Integrative Model of Bangla Origins Based on genetic evidence, the origins of the Bangla people can be summarized as follows: Primary descent from ancient South Asian populations Moderate Indo-Aryan Steppe-related ancestry Significant East and Southeast Asian gene flow Long-term regional admixture shaped by geography and history This integrative model aligns with linguistic and archaeological evidence for Bengal as a dynamic cultural and genetic frontier. 9. Conclusion The Bangla people of Bangladesh represent a genetically distinctive South Asian population shaped by ancient indigenous ancestry, Indo-Aryan expansions, and sustained interaction with East and Southeast Asian populations. Their genetic profile reflects Bengal’s geographic position at the eastern edge of the Indian subcontinent and its long history as a hub of migration and cultural exchange. Overall, Bangla ethnogenesis is best understood as a process of genetic continuity combined with regional admixture, rather than a single origin event. Future ancient DNA research from eastern South Asia will further refine our understanding of this population’s deep history. References Reich, D. et al. (2009). Reconstructing Indian population history. Nature, 461, 489–494.Metspalu, M. et al. (2004). Most of the extant mtDNA boundaries in South and Southwest Asia were likely shaped during the initial settlement of Eurasia. BMC Genetics, 5, 26.Sengupta, S. et al. (2006). 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