Before the arrival of the first European settlers to the east coast of Australia in 1788 the area that now forms the suburbs of Beecroft and Cheltenham was occupied by the Wallumeda, a Darug speaking people, who lived in the area between the Parramatta and Lane Cove Rivers.
Something of the original aspect of the area can still be seen in the open forest in the Ludovic Blackwood Memorial Sanctuary, near the intersection of Pennant Hills and Beecroft Roads. The forest provided the indigenous inhabitants with a diet of vegetable foods and berries as well as birds and small animals. The waterways, especially Devlins Creek, a major tributary of the Lane Cove River, provided fish and shellfish. There are now few remaining signs of the Wallumedas' occupation, but their shelters were probably huts and caves such as the north-facing cave on the southern bank of Devlins Creek in the Beecroft Reserve.