The stdy of prehistory is subject to the same bias and prejudice as any other scientific discipline. When the rewards are likely to be few and the effort required great, researchers will avoid problem areas in favour of more lucrative fields. One such neglected area of research has been the archaeology of the coastal plains and forests of southeastern Australia, where poor visibility and the diffuse nature of the archaaeological record militate against the investment of valuable research time. In the Sydney region, the archaeological data accumulated relate almost exclusively to rock shelter deposits. While such sites do have the potential to provide a great deal of valuable information, they reflect only a fraction of the activities carried out by the prehistoric population. In order to counteract the bias evident in the archaeological investigations, I undertook a systematic archaeological survey of the western Cumberland Plain. In the early chapters of this thesis, I examine the environmental setting and the resources which were available to Aboriginal people at the time of European settlement in 1788. After evaluating the ethnographic accouns, a clear picture emerges of two major economic systems operating; one based on coastal resources and one reliant on a wider range of locally abundant foods. Associate with this dichotomy were linguistic, technological and social differences suggestive of dense Aboriginal populations exploiting relatively narrow territories. Archaeological surveys were undertaken, a representative rockshelter site and two open sites were excavated, and, in conjunction with the surface collection of artefacts, it was possible to identify patterns in the archaeological record suggesting that the technological changes evident in the stone tools were a reflection of a changing resource base. In the final chapters, te factors which have influenced the location of sites and the distribution of artefact types are examined, and a model proposed which accounts for the observed data. The model suggests that macropodids formed a major component of the diet for several thousand years following the introdution of a microlithic industry, but that over the last 2,000 years increasing Aboriginal population has necessitated a diversification into a wider range of resources.