Background: The Indian peninsula provides a suitable region for examination of the demographic impact of migrations and invasions in historical times, because its complex recent history has involved the long-term residence of different populations with distinct geographical origins and their own particular cultural characteristics.Aim: The aim of the present study was to analyse Y chromosome haplotypes in tribes from eastern and north-eastern India, which provided the necessary phylogeographic resolution.Subjects and methods: A total of 32 Y-chromosome SNPs and 17 Y-STRs were genotyped in 607 males from nine populations (Munda, Birhor, Oraon, Paharia, Santhal, Ho, Lachung, Mech and Rajbanshi) residing in East and Northeastern India.Results: Y-chromosomal analysis revealed high frequency of the O2a haplogroup in Austroasiatic tribes and high haplotype diversity within specific haplogroups demonstrating a lesser degree of admixture of these populations with neighbouring populations in eastern India. In addition, the presence of O3a haplogroups in Sino-Tibetan populations reflects the influx from Southeast Asia during the demographic expansion through the Northeastern corridor.Conclusion: The study suggested that the majority of the male gene flow of Austroasiatic tribes occurred during the late Pleistocene period. The results suggest gene flow from Southeast Asia to Northeast India, albeit more significantly among Tibeto-Burman than Austroasiatic-speaking populations.