The indigenous population, estimated to have been between 750,000 and 1,000,000 in 1788, declined for 150 years following settlement, mainly due to infectious disease. Thousands more died as a result of frontier conflict with settlers. A government policy of "assimilation" beginning with the Aboriginal Protection Act 1869 resulted in the removal of many Aboriginal children from their families and communities—often referred to as the Stolen Generations—a practice which may also have contributed to the decline in the indigenous population. As a result of the 1967 referendum, the Federal government's power to enact special laws with respect to a particular race was extended to enable the making of laws with respect to Aborigines. Traditional ownership of land ("native title") was not recognised in law until 1992, when the High Court of Australia held in Mabo v Queensland (No 2) that the legal doctrine that Australia had been terra nullius ("land belonging to no one") did not apply to Australia at the time of British settlement.