English: Although deriving 80–92% of their ancestry from a lineage related to Upper_YR_LN (Supplementary Table 4), the aMMD and present-day Sherpa/Tibetans are not adequately modeled as a sister clade to Upper_YR_LN, as expected given the unique genetic components of Tibetans not shared with lowlanders, including the EPAS1 allele from a Denisovan-related admixture. Rather, the remaining 8–20% of their ancestry derives from a deep part of the population graph near the split between Western and Eastern Eurasian branches (Fig. 3; Supplementary Fig. 9). This source, however, does not derive from archaic hominins (Neanderthals or Denisovans, who contribute <0.5% genome-wide ancestry), and our results reject previously suggested sources of gene flow into the Tibetan lineage13,35,36, including deeply branching Eastern Eurasian lineages, such as the 45,000-year-old Ust’-Ishim individual from southern Siberia, the 40,000-year-old Tianyuan individual from northern China, and Hoabinhian/Onge-related lineages in southeast Asia (Supplementary Fig. 10), suggesting instead that it represents yet another unsampled lineage within early Eurasian genetic diversity. This deep Eurasian lineage is likely to represent the Paleolithic genetic substratum of the Plateau populations.