The study, "Extended Y Chromosome Investigation Suggests Postglacial Migrations of Modern Humans into East Asia via the Northern Route," analyzes the genetic structure of the male Y-chromosomal lineage in East Asia, focusing on the contribution of populations from Central and South Asia (CSA) and Western Europe (WE) and migrations after the last glacial maximum. Four dominant Y-DNA haplogroups, O-M175 (63.75%), D-M174 (10.72%), C-M130 (12.43%) and N-M231 (5.96%), were identified from the 3826 males studied from 117 populations in China and North Korea. They account for a total of 92.87% and are of southern origin, confirming the dominant role of the southern route of human migration to East Asia in the Paleolithic. However, haplogroups typical of CSA and EC (including Q-M242 and R-M207) were detected in 6.79% of individuals, mainly in Northeast Asian (NEAS) populations. Their geographic distribution and analysis of Y-STR marker diversity suggest that they arrived in NEAS via a northern route, both in the postglacial period (~18,000 years ago) and later (~3,000 years ago). In particular, Q-M242 (precursor of Q1a3a-M3, typical of Native Americans) and R-M207 represent old migrations through Siberia. Analysis of haplotype differences and the age of Y-STR mutations indicates that lineages such as R1a1*-M17 and Q1a1-M120 have ancient origins and high diversity in East Asia, suggesting local diversification after migration from CSA/WE. Some lineages (e.g., R1b-M269, J2a-M410) may originate from Neolithic expansion from the Middle East. These results confirm the major contribution of the southern route to the settlement of East Asia, but also reveal the important, albeit limited, contribution of post-glacial migrations via the northern route to the genome of Northeastern populations. The differences between SEAS and NEAS reflect these diverse genetic sources.