Our recent discovery and excavation of a series of iron smelting furnaces, dated to the eighth and ninth century CE, near upland Rmet villages in northwest Laos, potentially sheds new light on the role of regional upland groups during the immediate pre-Tai period. The oral tradition associated with these furnaces emphasises the role of an ancient population of metallurgists who left the area under pressure from the Rmet. These stories could refer to the actual arrival and departure (immigration and emigration) of a population of metallurgists in that area sometime during the second half of the first millennium CE or they can support the scenario of a dissimilation process. The latter would explain the existence of a Rmet subculture that the locals regard as ‘Chueang Lavae’ villages, a differentiation that Karl G. Izikowitz had labelled ‘Upper Lamet’ in the 1930s. Our finds show that archaeology and ethnology can both contribute to a much-needed reformulation of upland Lao history.