It is becoming increasingly evident that humans have migrated throughout their existence. These migrations often took place over relatively small distances, for instance for local trade or exchange of marital partners. However, migrations over surprisingly long distances are known as well, such as the Austronesian expansion that carried peoples out of Taiwan across vast expanses of the Pacific up to Hawai’i and New Zealand in the east, and all the way to Madagascar in the west. Such migrations can bring peoples into contact that have very different cultural and linguistic backgrounds and can lead to genetic admixture, cultural exchanges, language contact and language shift. From a linguistic perspective, the outcome of such migrations - contact and shift - are of major importance, since they can have an impact on the structure of languages. Historical linguists can potentially detect features such as substrate phonology, loanwords, or contact-induced structural changes which, if they remain undetected, might skew our understanding of the linguistic relationship and prehistory of the languages concerned. However, it is often difficult to interpret such features if nothing is known about the original contact situation. Furthermore, it is not possible to date migrations and contact using linguistic data. Further insights into the effects of prehistoric migrations can be gained with the help of genetic investigations. The genomes of people living today retain traces of the historic processes which their ancestors underwent, and molecular anthropologists can use these to elucidate the unwritten past. For instance, molecular anthropological analyses can provide indications of prehistoric admixture events, sex-biased migration patterns, decreases or increases of population size, and settlement practices (matri- vs patrilocality). These results allow insights into the prehistoric sociocultural practises that may have had an effect on language change in contact situations. With modern computational techniques, it is furthermore possible to date these events to obtain additional insights into the processes that might have shaped the languages spoken today in a particular region. In this talk, I will provide an overview over the added value that can be obtained when historical linguistic studies are combined with insights coming from molecular anthropological analyses, illustrating this approach with case studies from around the world.