The Lao historiographical tradition places the introduction of Buddhism with the newly created Lan Xang kingdom in the middle of the fourteenth century ce, through a religious mission that travelled from Cambodia to Luang Prabang. Critical analysis of the chronicles, as well as new awareness of the extent of pre-Angkorian, Mon and Angkorian inuences in the Middle Mekong Valley, however, lead us to profoundly review this assertion. Early Khmer remains found scattered around Luang Prabang appear to be singularly isolated, and their presence in upper Laos requires further explanation.