The Western Grey is not found in the tropical north or the fertile south-east of Australia . The Eastern Grey is not found over the NSW-South Australia border , but the two species are both common in the Murray-Darling Basin area . The Western Grey is not found in the tropical north or the fertile south-east of Australia , and the Eastern Grey does not extend beyond the NSW-South Australia border , but the two species are both common in the Murray-Darling Basin area .