Since the realisation in the second half of the 18th century that Sanskrit, Persian and most European languages are related, linguists have been able to reconstitute a basic grammar, a core vocabulary, and even a poetics of how the basic language from which all these other languages evolved. Historians of religion and archaeologists have attempted to reconstruct the spiritual and social life of these groups. The advent of ancient DNA (aDNA) has made it possible to clear up an old puzzle, namely where the speakers of proto-Indo-European were based. They turn out to be the first colonizers of the Eurasian steppe, and were based north of the Black Sea. This 2019 Christmas lecture from the Norwegian Academy of Sciences gives an overview of extant knowledge and stresses that ever new waves of incoming steppe people have played a key, but until now largely unacknowledged, role in European state formation.