Roman civilisation started its climb maybe 500 BC or so at its oldest. This study says these genes were introduced circa 2000 BC.
I saw that but the hypothesis seemed to be "Iron Age migration" without considering other factors or explaining why they though the DNA was already there before the Roman conquest at the time of Clauduis.
Maybe the geneticist was used to thinking in terms of peaceful migrations and not in terms of strategic military retreats, desperate military stands and the defensibility of montainous regions as compared to the lowlands.
In Spain, at the shock of the Moorish invasion in 711 A.D., the Visogothic DNA that had been concentrated in central and southern Spain, within a couple of years, became concentrated in Asturias. This had nothing to do with peaceful migrations and everything to do with strategic military retreats and the defensibility of the Cantabrian Mountains.