Movements of people from one place to another, also referred to as human migrations, played a fundamental role in the history of archaic and modern humans. Here, current evidence and hypotheses on two major prehistoric human migrations are described: the initial colonization of Eurasia by archaic and modern humans, and the Neolithic expansion of modern humans into Europe, and how they shaped human genetic diversity. Furthermore, current genetic evidence on admixture between modern and archaic humans is discussed, and showed based on two populations well-known for their particular migration history it is exemplified how genetic diversity can be used to trace population origins and migration history.