After European nations settled Australia between 1700-1800, the native population (Aboriginal Australians) began to decline. Although disease spread from the European settlers was a major factor, the advent of The Stolen Generations -- a time when the government and church removed Aboriginal children from their families to raise them in European society -- marked a direct attack on Aboriginal culture and history.
Originally, the attempt to "civilize" Aborigines came from the typical attitude of the era, that native peoples were simple and child-like and therefore needed to be taught how to think and act. Essentially, the government tried to assimilate the Aborigines "for their own good," as if civilization was something that they wanted rather than something forced on them. The result was the decimation of Aboriginal culture and population; children who were raised in modern society often developed drug and alcohol addictions, and had a higher incidence of suicide. The removal of children was done without parental consent, although some families were compensated financially; an unknown number of children, between 20,000 and 100,000, were removed, and the famous 1997 report "Bringing Them Home" stated that "...not one family has escaped the effects of forcible removal" (Wikipedia).
Public opinion towards treatment of indigenous peoples changed gradually during the 1900s, and today the Aboriginal population is estimated at 500,000, with civil and legal protections afforded by the government.