Assuming that humans dispersed into Asia predominantly via a southern coastal route is firmly rooted in conventional wisdom. But, the evidence is far more equivocal on the question.
Northern and Central Asia have been neglected in studies of early human migration, with deserts and mountains being considered uncompromising barriers. However, a new study argues that humans may have moved through these extreme settings in the past under wetter conditions. By analyzing past climate, northern Asia emerges as a potential route of human dispersal, as well as a zone of potential interaction with other hominins such as Neanderthals and Denisovans.From here.
Feng Li, Nils Vanwezer, Nicole Boivin, Xing Gao, Florian Ott, Michael Petraglia, Patrick Roberts. "Heading north: Late Pleistocene environments and human dispersals in central and eastern Asia." PLOS ONE, 2019; 14 (5): e0216433 DOI: 10.1371/journal.pone.0216433