The prehistory of Australia is the period between the first human habitation of the Australian continent and the colonization of Australia in 1788 which marks the start of consistent documentation of Australia. This period is estimated to have lasted between 40,000 and 60,000 years.
This era is referred as prehistory rather than history because there are no remaining written records of human events before 1788.
There is considerable discussion among archeologists as to the route taken by the first migrants to Australia, widely taken to be ancestors of the modern Aborigines. Migration took place during the closing stages of the , when sea levels were much lower than they are today. Repeated episodes of extended glaciation during the Pleistocene epoch resulted in decreases of sea levels by more than 100 metres in Australasia. People appear to have arrived by sea during a period of glaciation, when New Guinea and Tasmania were joined to the continent of Australia.
The continental coastline extended much further out into the Timor Sea, and Australia and New Guinea formed a single landmass (known as Sahul), connected by an extensive land bridge across the Arafura Sea, Gulf of Carpentaria and Torres Strait. Nevertheless, the sea still presented a major obstacle so it is theorised that these ancestral people reached Australia by island hopping. Two routes have been proposed. One follows an island chain between Sulawesi and New Guinea and the other reaches North Western Australia via Timor.Rupert Gerritsen has suggested an alternative theory, involving accidental colonization as a result of tsunamis. The journey still required sea travel however, making them amongst the world's earlier mariners.
Scott Cane wrote in 2013 that the first wave may have been prompted by the eruption of Mount Toba and if they arrived around 70,000 years ago could have crossed the water from Timor, when the sea level was low - but if they came later, around 50,000 years ago, a more likely route would be through the Moluccas to New Guinea. Given that the likely landfall regions have been under around 50 metres of water for the last 15,000 years, it is unlikely that the timing will ever be established with certainty.