Invasion theory

Invasion theory or Invasionism is a method of explaining changes in past societies that relies on the idea of external conquest to provide the catalyst for new ideas appearing in a culture, the arrival of novel artefact types or building styles appearing in the material record for example.

Invasionism was a popular approach to explaining social change amongst archaeologists until the 1960s when approaches that treated prehistory as being less bellicose were increasingly adopted, such as migrationism.

It is connected with early twentieth century ideas of diffusionism and hyper-diffusionism which often hinged on Biblical mass folk movements and successive waves of invaders providing infusions of new ideas in different regions.

Although the approach has generally been superseded it is still applicable in certain cases. However its application is treated to much more scrutiny that it was previously and such theories now require concrete proof rather than being given an assumption of veracity.