Scientists are correlating the genetic features of different races with their territory. Many of the genetical groups have restricted locations.
The patches of strong colour in the map represent distinct genetic features, based on human genome data. They follow familiar geographic features such as mountain ranges, sea barriers and deserts.
In Asia, the migration routes have been recognised for some time.
(See Nature October 13. 2016: Genomic analyses inform on migration events during the peopling of Eurasia – by Luca Pagani et al)