Gordon Childe thought that the people were missionaries, who also had the knowledge how to make copper. They spread from the Iberian peninsula on the "edges" of Europe with the oceans. The typical items linked to the movement were prestige items reserved to the upper class, according to Steven Shennan. Christian Strahm talk about a "Glockenbecherphänomen" (bell-shaped cup phenomenon), to avoid the word "culture".