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Haplogroup O1b-F3651

O1b-F3651 (mainland East/Southeast Asian early lineage)

Macro-haplogroup
K
Parent clade
O-M175
Formed (estimate)
c. 25,000–30,000 years before present
TMRCA (estimate)
c. 15,000–18,000 years ago

Overview

O1b-F3651 is a foundational paternal lineage in mainland East and Southeast Asia. Unlike O1a, which is strongly tied to Austronesian maritime expansions, O1b represents early inland and riverine population movements across southern China, northern Vietnam and the Mekong basin. This clade predates the formation of well-known Austroasiatic and Kra-Dai linguistic groups and formed part of the Neolithic demographic substrate that shaped much of mainland Southeast Asia.

Geographic distribution

Today O1b peaks in East Asia (Korea, Japan) and mainland Southeast Asia (Vietnam, Thailand, Laos). It is common among several Kra-Dai and Austroasiatic-speaking groups, as well as among Japanese and Koreans, highlighting ancient continental interactions.

Ancient DNA

  • Ancient samples from Neolithic coastal China and inland river valleys show O1b-related paternal ancestry.
  • O1b lineages are associated with early farming populations in the Pearl River and Red River regions.
  • Its age predates the split of major mainland language families.

Phylogeny & subclades

O1b divides into two large and well-studied branches: O1b1 (which includes the M95 lineage) and O1b2 (formerly linked to Japanese and Korean paternal diversity). This split creates the core geographic pattern of mainland Asian O lineages.

  • O1b1
  • O1b2

Notes & context

O1b-F3651 is crucial for modeling the demographic origins of mainland East and Southeast Asia.