The Industries of Angkor Project (INDAP) is the first scientific study combining investigation of the chronology, supply network and technology of raw and finished iron within Angkorian (9th to 15th c. AD), Middle Period (15th to 19th c. AD) and Colonial (1863–1953) Cambodia. This paper is concerned with the production technology employed at five iron smelting sites in the northern province of Preah Vihear, three loci within the enclosure walls of the Angkorian Preah Khan complex and two, c. 30 km east, near Phnom Dek or ‘Iron Mountain’. The Phnom Dek area is a historic homeland of the ethnic minority Kuay people, who continued to smelt iron from local mineral sources into the 1940s. With the aim of testing a previously proposed ‘Angkorian Kuay’ hypothesis, that Kuay ancestors were responsible for Angkorian period iron smelting at Preah Khan of Kompong Svay (Preah Khan), the objective of this preliminary study was to establish whether any technological continuity could be detected across a 1200 year old industrial landscape, and thus if any socio-culturally homologous relations could be proposed for the ironmakers respectively responsible. Our preliminary results suggest that the iron smelting remains at Preah Khan date from Angkor's terminal phase and into the subsequent Middle Period, whereas as the two studied production sites near Phnom Dek range from the 9th–11th c. AD and to the 19th/20th c. AD. Preah Khan and Phnom Dek production systems appear to have used different iron ore sources but, in the absence of well-preserved furnace remains, statistical analysis of slag chemistry indicates a technological conservatism spanning more than a millennium. At this stage the ‘Angkorian Kuay’ model can be neither rejected nor sustained but the complexity of Preah Vihear province's settlement and industrial history is becoming increasingly apparent and will only become clearer with further excavation and study of chronologically and geographically intermediate sites. © 2014, Elsevier Ltd.