The spread of ideas, items of material culture, or cultural traits from one culture or society to another. Diffusion does not necessarily imply a movement of people, for ideas can move through trade and other forms of contact. What it does imply is that ideas and inventions tend to radiate out from one source area into surrounding regions. Prior to radiocarbon dating there was a general assumption that, within the Old World, most of the main developments and key innovations took place in the Near East, the Middle East, Egypt, and the Mycenaean world of Greece and the Aegean, and ideas spread out from there. Taken at its extreme, in what is sometimes known as hyper‐diffusionism, major inventions happened only once, and a few key areas provided the inspiration for most major technical and social developments later imparted to the rest of the world: such things as agriculture, writing, urban settlement, metallurgy, and so on. It is now recognized, however, that many things were independently developed under different social conditions at different times. Moreover, radiocarbon dating has shown that the movement of ideas is far more complicated than originally thought and that it is inappropriate to think in terms of simple one‐way movements outwards from supposedly ‘higher civilizations’. Compare acculturation.