Migrationism and diffusionism

In the history of archaeological theory the term migrationism was opposed to the term diffusionism (or "immobilism") as a means of distinguishing two approaches to explaining the spread of prehistoric archaeological cultures and innovations in artefact. Migrationism explains cultural change in terms of human migration, while diffusionism relies on explanations based on trans-cultural diffusion of ideas rather than populations (pots, not people).

Western archaeology the first half of the 20th century relied on the assumption of migration and invasion as driving cultural change. This was criticized by the processualist in the 1960s and 1970s, leading to a new mainstream which rejected "migrationism" as outdated. Since the 1990s, there has been renewed interest in "migrationist" scenarios, as archaeologists attempted the archaeological reflexes of migrations known to have occurred historically. Since the 2000s, the developments in archaeogenetics have opened a new avenue for investigation, based on the analysis of ancient DNA.

Kristiansen (1989) argued that the reasons for embracing "immobilism" during the Cold War era was ideological, derived from an emphasis on political solutions displacing military action.

In British archaeology, the debate between "migrationism" and "immobilism" has notably played out in reference to the example of the Anglo-Saxon settlement of Britain.

"Diffusionism" in its original use in the 19th and early 20th century did not preclude migration or invasion. It was rather the term for assumption of any spread of cultural innovation, including by migration or invasion, as opposed "evolutionism", assuming the independent appearance of cultural innovation in a process of parallel evolution, termed "cultural evolutionism".

Opposition to migrationism as argued in the 1970s had an ideological component of anti-nationalism derived from Marxist archaeology, going back to V. Gordon Childe. Childe in the interwar period combined "evolutionism" and "diffusionism" in arguing an intermediate position that each society developed in its own way, but strongly influenced by the spread of ideas from elsewhere. In contrast to Childe's moderate position, which did allow the diffusion of ideas and even moderate migration, Soviet archaeology adhered to a form of extreme evolutionism, which explained all cultural change due to the class tensions internal to prehistoric societies.

...
Wikipedia