The Germanic branch (S21/U106/M405). The principal Proto-Germanic branch of the Indo-European family tree is R1b-S21 (a.k.a. U106 or M405). This haplogroup is found at high concentrations in the Netherlands and north-west Germany. It is likely that R1b-S21 lineages expanded in this region through a founder effect during the Unetice period, then penetrated into Scandinavia around 1700 BCE (probably alongside R1a-L664), thus creating a new culture, that of the Nordic Bronze Age (1700-500 BCE).