[3] In any event, this migration was achieved during the closing stages of the Pleistocene epoch, when sea levels were typically much lower than they are today.
It is theorised that these original peoples first navigated the shorter distances from and between the Sunda Islands to reach Sahul; then via the land bridge to spread out through the continent.
As the sea levels again rose at the terminus of the most recent glacial period some 10,000 years ago the Australian continent once more became a separated landmass.
However, the newly formed 150 km wide Torres Strait with its chain of islands still provided the means for cultural contact and trade between New Guinea and the northern Cape York Peninsula.
[4] According to a 2013 German study by a team of researchers on Indigenous Australian DNA genes reveal that a wave of migrants from India arrived in Australia about 4,230 years ago.
It shows that the Indian migrants settled in Australia before Captain James Cook's first recorded contact with the Australian coastline.
This study overturns the view that Australian continent was isolated from the time it was first colonised about 45,000–50,000 years ago until Europeans discovered Australia in the eighteenth century.
Professor Alan Cooper, from the University of Adelaide's Centre for Ancient DNA, says that the Indian influence may well have played a role in the development of the Australian Aboriginal culture.
It continued to the colonies of Van Diemen's Land (where settlement began in 1803) and Moreton Bay (founded 1824, and later renamed Queensland) for some years longer.
The small settlement of Perth, founded in 1829 on the Swan River in Western Australia by free settlers, failed to prosper and asked for convicts.
South Australia not only received British migrants, but also a significant influx of Prussian farmers and tradesmen, initially seeking freedom from religious persecution.
From about 1815 Sydney began to grow rapidly as free settlers arrived from Britain and Ireland and new lands were opened up for farming.
Despite the long and arduous sea voyage, settlers were attracted by the prospect of making a new life on virtually free land.
The discovery of gold, beginning in 1851 first near Bathurst in New South Wales and then in the newly formed colony of Victoria, transformed Australia economically, politically and demographically.
The government found that if it wanted immigrants it had to subsidise migration; the great distance from Europe made Australia a more expensive and less practical destination than Canada, the United States, Brazil or Argentina.
"[13] A predominantly European nation on the periphery of Asia, historically many white citizens of Australia feared being demographically overwhelmed by the heavily populated Asian countries to the north.
Following the attacks on Darwin and the associated fear of Imperial Japanese invasion in WWII, Minister of Immigration Arthur Calwell stated in 1947: "We have 25 years at most to populate this country before the yellow races are down on us."
This concern about Australia's demographic vulnerability was a driving force behind the country's massive post-war program of European immigration.
For the first time, in a revolutionary step for both Australian society and international relations, Australia looked outside Britain for migrants.
The Australian government assisted many of the refugees, such as helping them find work (due to an expanding economy and major infrastructure projects, the Snowy Mountains Scheme being the most famous).
During that twenty years, Australia first began to adopt a policy of what Minister of Immigration Al Grassby termed "multiculturalism".
[22] Refugees that are granted a protection visa are eligible for standard social security benefits such as New start and Rent Assistance.
[23] In the early 1990s Australian immigration legislation was changed dramatically, introducing the concept of mandatory detention of unauthorised arrivals, who were popularly referred to as boat people.
This was a major factor contributing to the victory of the Coalition, deemed impossible only a few months earlier, and also marked the beginning of the controversial Pacific Solution.
Others argued that the decrease was the result of global factors, such as changing circumstances in the primary source nations of Afghanistan and Iraq.
In March 1984, Professor Geoffrey Blainey, an Australian historian, made a speech criticizing what he saw as disproportionately high levels of Asian immigration to Australia.
In her maiden speech to the House of Representatives after her election in 1996, Pauline Hanson expressed her concern that Australia "was in danger of being swamped by Asians".