Culture diffusion has long been a key source of change in society. Some of the changes that occurred during Old Stone age, Neolithic age, and at the time of Early Civilizations were likely the result of cultural diffusion. Culture diffusion affects the way people interact in and behave very deep ways. Since culture moves with people, and people do not move with homogeneously but in waves, and on the front of this wave is technology or way of life. The magnitude of trade and other agreements depends on the similarity between the two cultures. A culture that interacts will be exchanging people, culture an ideas, and will become similar according to how strongly this occurred.