Analysis of 28 radiocarbon determinations obtained from the excavation of heat retainer hearths from Sturt National Park in western New South Wales, indicates Aboriginal occupation of the arid margin of Australia during the last 1700 years. The determinations show two phases of hearth construction separated by a period of at least 200 years, and possibly 400 years, when no hearths were constructed. Palaeoenvironmental and archaeological evidence is reviewed in an effort to account for the late Holocene dates from the hearths and the existence of the hiatus in hearth construction. Despite the close match between the hiatus and the so-called Medieval Warm Period, caution is required before extrapolating the results from an archaeological study of a small geographic region to the continent as a whole.