Overview
Haplogroup R-PH127 is a deeply rooted upstream branch within the R2a phylogeny, representing one of the earliest identifiable divergences after the formation of R2a from ancestral R2-M124 populations. It likely emerged during the early Holocene in a wide territory connected through seasonal mobility routes between Iran, Turan and northwest South Asia. Its position high in the R2a tree makes it particularly important for reconstructing the structure of the lineage during its formative stages. PH127 appears in extremely low modern frequencies, typically detected through whole-genome or high-resolution Y-chromosome sequencing. Its presence in Iran, Turkmenistan, Afghanistan and rarely northern India suggests that the lineage persisted within ancient populations engaged in flexible subsistence strategies, including mixed foraging and pastoralism. These groups formed a demographic substrate that predated the full establishment of agrarian settlement systems in the region. Although no ancient individuals belonging specifically to PH127 have been found, several early R2-related samples from the Iranian Plateau and Bactria–Margiana Archaeological Complex (BMAC) territories illustrate that R2a-bearing populations were widely diffused across the region by the time PH127 emerged. As an early diverging branch, PH127 is critical for understanding how R2a diversified before the later, more concentrated expansions in South Asia.