We can do little better than guess at the Aboriginal population of the Sydney district before 1788. Governor Phillip estimated the population of the areas he visited in the first weeks of settlement as 1500 but there is no way of checking how accurate his conjecture was. A number of estimates of the population density of the coastal fringe have been made but there is little agreement between them. K Maddock has estimated the Sydney population to have been 2 to 4 people per square kilometre but this appears to be too high. Taking coastal Sydney only, an area of about 1300 square kilometres, Maddock's estimates gives a population between 2600 and 5200 people with the inland numbers still to be added. In 1946, the Arnhem Land Reserve , with an area twenty times larger than the Sydney district and certainly as fertile a region as our own, maintained a population of no more than 4000 Aborigines.
Another estimate of the population density of coastal environments, reported by Derek Mulvaney, is between 0.05 to .02 people per square kilometre. For the coastal part of Sydney mentioned above, this estimate gives population figures of 65 to 260. Based on a survey of Aboriginal numbers ordered by Governor Phillip in July 1788, these figures seem to small. The survey recorded the presence of 94 men, 34 women and 9 children around the shores of Port Jackson. Although only 34 women were seen, it seems likely that the numbers of men and women were roughly equal, indicating that the Port Jackson area supported atleast 200 people.
It is not unreasonable, therefore, to allocate a population of 200 to the Georges River- Port Hacking district and a similar number to the Hawkesbury River and its southern tributaries. We now have a population of 600 without including Aborigines of the inland. There are no population figures for the area west of Parramatta but it is reported that the population density of the interior was lower than that on the coast.
The discovery of a large gathering of Aborigines near Long Bay in June 1788 during Governor Phillip's investigation of the killing of two rushcutters provide some interesting, if inadequate, data on the population of the district.At least 300 people were seen and 212 of them were men. Again assuming that there was a similar number of women(in fact, there may have been more women than men) this indicates a population of atleast 400.
The problem is, of course, that we don't know where these people came from. Those in attendance may represent only a part of the Sydney population or alternatively, may have been drawn from an area larger than the Sydney district. Long Bay was probably in the Cadrigal horde's territory so they were certainly there, while the discovery of 49 canoes on the beach at nearby Congwong Bay suggests that the Gweagals or Bidjigals, or both, were also present. Unfortunately, this is all we know about the origins of the people attending. The gathering was probably the largest observed by Europeans in the region because the smallpox epidemic struck the following year.