Anecdotally, I have noticed that some Cambodians have distinctly Indian features (not necessarily australoid) and do not resemble other east asians.

I have highlighted certain notable points for your ease.

The first colonists would thus have needed boats to cross some narrow seas in order to settle this land. But since their ancestors would have required similar craft to cross Bab el Mandeb, no technological improvement would have been required for them to do so.

Dr Pugach, however, also discovered something else. There is a pattern of SNPs in aboriginal Australians that is not found in people from New Guinea or the Philippines. But it is found in some Indians—particularly from the southern part of the subcontinent. That discovery both meshes with the Y-chromosome data and enriches it, because the pattern of the SNP data meant that she and her colleagues could calculate when the Indian genes (and thus the Indians who carried them) arrived in Australia.

The answer is 141 generations ago. Allowing 30 years a generation, that yields a date of 2217BC. Obviously, this is not a precise date. But it is probably good to within a century or two. And that is interesting for two reasons. One is that the 23rd century BC is slap-bang in the middle of the period when Indian civilisation was emerging. The other is that it coincides with a shift in both the culture of Australia and the composition of the continent’s wildlife.

One technology it managed to develop was seaworthy ships, rather than mere boats, and Indus valley states used them to trade with their Middle Eastern neighbours. Such ships could have provided the means to get to Australia, either deliberately or by accident, for by then the sea had risen close to its modern level.

The second shift was gastronomic. Sadly, the archaeological record has yet to reveal tandoori ovens or fossilised chapatis in Australia. But it does show changes at this time in the ways that cycad nuts—an important crop that Australians had long cultivated by the “fire-stick” method of burning vegetation that competes with the trees that bear them—were processed. Such nuts contain toxins. After about 2000BC several methods for removing these toxins, such as leaching them out with water and fermenting them away, spread through Australia. To this day, cycad nuts are familiar food in Kerala, in southern India. There, they are detoxified by being dried in the sun or by the fireside.

The third thing that arrived in Australia at this time was the dingo. The origin of these wild dogs, which are believed to have outcompeted and exterminated the native thylacine (also known as the Tasmanian tiger, because it lingered into modern times on that dingo-free island), has always been obscure, though their resemblance to certain breeds found in India is well known. Dr Pugach’s discovery suggests they may have come directly, on board ship. However, the existence of similar dogs in New Guinea and parts of South-East Asia complicates that explanation.

If metal objects or forges were to be found in Australia, I could accept the theory.  I, however, cant imagine that extensive contacts occurred with out either transmitting metallurgy to the indigenous peoples, or the Indian colonists establishing metal producing capabilites in Australia.

Archaeologists divide Mesoamerican civilizational development into three major time periods: the PreClassic or Formative period extending from 1500 B.C. - A.D. 300, the Classic period extending from A.D. 300-950, and the PostClassic period extending from A.D. 950-1521.