 Using a multidisciplinary approach, Alberto J. Lorrio and Gonzalo Ruiz Zapatero reviewed and built on Almagro Gorbea's work to present a model for the origin of the Celtic archaeological groups in the Iberian Peninsula (Celtiberian, Vetton, Vaccean, the Castro culture of the northwest, Asturian-Cantabrian and Celtic of the southwest) and proposing a rethinking of the meaning of "Celtic" from a European perspective.More recently, John Koch and Barry Cunliffe have suggested that Celtic origins lie with the Atlantic Bronze Age, roughly contemporaneous with the Hallstatt culture but positioned considerably to the West, extending along the Atlantic coast of Europe.Stephen Oppenheimer points out that the only written evidence that locates the Keltoi near the source of the Danube (i.e.