 In 664, the Synod of Whitby began to resolve these differences, mostly by adopting the current Roman practices, which the Gregorian Mission from Rome had introduced to Anglo-Saxon England.In a March 2019 genetic study published in "Science", three Celtiberians buried at La Hoya, Salamanca between 400 BC and 195 BC were examined.They were find to be harboring elevated levels of north-central European ancestry compared to non-Celtic populations of Iberia.