Australia experienced a wave of migration from India about 4,000 years ago, a genetic study suggests.
It was thought the continent had been largely isolated after the first humans arrived about 40,000 years ago until the Europeans moved in in the 1800s.
But DNA from Aboriginal Australians revealed there had been some movement from India during this period.
The researchers believe the Indian migrants may have introduced the dingo to Australia.
In the Proceedings of the National Academy of Sciences, they say that the fossil record suggests the wild dogs arrived in Australia at around the same time.
They also suggest that Indians may have brought stone tools called microliths to their new home.
"For a long time, it has been commonly assumed that following the initial colonization, Australia was largely isolated as there wasn't much evidence of further contact with the outside world," explained Prof Mark Stoneking, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
"It is one of the first dispersals of modern humans - and it did seem a bit of a conundrum that people who got there this early would have been so isolated."
To study the early origins of Australia's population, the team compared genetic material from Aboriginal Australians with DNA from people in New Guinea, South East Asia and India.
By looking at specific locations, called genetic markers, within the DNA sequences, the researchers were able to track the genes to see who was most closely related to whom.
They found an ancient genetic association between New Guineans and Australians, which dates to about 35,000 to 45,000 years ago. At that time, Australia and New Guinea were a single land mass, called Sahul, and this tallies with the period when the first humans arrived.
But the researchers also found a substantial amount of gene flow between India and Australia.
Prof Stoneking said: "We have a pretty clear signal from looking at a large number of genetic markers from all across the genome that there was contact between India and Australia somewhere around 4,000 to 5,000 years ago."
He said the genetic data could not establish the route the Indians would have taken to reach the continent, but it was evidence that Australia was not as cut off as had been assumed.
"Our results show that there were indeed people that made a genetic contribution to Australians from India," Prof Stoneking explained.
The researchers also looked at fossils and other archaeological discoveries that date to this period.
They said changes in tool technology and new animals could possibly be attributed to the new migrants.
Prof Stoneking said: "We don't have direct evidence of any connection, but it strongly suggestive that microliths, dingo and the movement of people were all connected."