The Outback is a harsh area within Australia, destroyed by the lingering decay of radiation. This is the result of the detonation of a fusion power core, obliterating the facility that contained it and leaving its parts scattered far and wide.
The Junkers are the only known members of humanity that survive within this region, though most seem to be altered physically and psychologically by the radiation.
Well before the Omnic Crisis, the land was home to settlers and survivalists, solar farmers and those that merely wanted to be left alone. After the Crisis ended, however, the land was taken and given to the omnic. The resulting battles between the displaced humans and robots eventually resulted in the blighted landscape seen today.