Chapter 6 discusses the uncertain place in Thai cultural memory of prehistory, knowledge of which achieved definition as a result of archaeological investigations by joint Thai and American missions in the 1960s and early 1970s. The discovery of Neolithic and Bronze Age sites in northeast Thailand—most famously Ban Chiang—that led American archaeologists to reject French colonial scholars’ theory of cultural diffusionism was linked closely to the Cold-War political and strategic alliance with the United States. As a byproduct of this alliance, a great amount of artifacts from Ban Chiang were transferred to The University Museum, Philadelphia. After the end of the Cold War, Ban Chiang received the validation of UNESCO World Heritage, but the place it occupies in Thai cultural memory remains marginal.