People within such social networks frequently co-operated
to exploit abundant resources during good seasons or to share
scarce resources during drought or flood. The links between groups
were based on kinship and marriage ties, common ceremonial affiliation
and shared ownership of, or responsibility for, sacred sites and
The geographic distribution, density and mobility of the Aboriginal
population were closely related to the availability or water,
food and other resources. Generally, the size of the bands did
not vary as much as the extent of the tract of land (called the
range) needed by each group for its survival. In the desert regions
of the Centre population densities as low as one person per 100
sq km reflected Aboriginal adaptation to a far harsher environment.
The Walpiri, for example, inhabited an area of nearly 40 000 sq
km, while the Wangkanguru even successfully adapted to the Simpson
Desert. In arid regions large territories allowed groups to survive
by foraging in a seasonal and systematic manner over vast areas.