Then, the whole Indus civilisation was wiped out by the invasions of the ancestors of the present-day Indians, or were they displaced to Australia?
By this time rising ocean levels had made the narrow channel between Sundaland and the New Guinea/Australia landmass too wide for easy access.
“...Then, the whole Indus civilisation was wiped out by the invasions of the ancestors of the present-day Indians, or were they displaced to Australia?...”
They were, evidently, wiped out by prolonged severe drought, occasioned by cometary or bolide impact. Blam or SunkenCiv can fill you in on this.
The lighter-skinned Aryans conquered India about 2000 BC, and took over from the darker-skinned people that were there before them. This is the origin of the caste system, where those who are mostly Aryan occupy the top caste, then are various mixes, and at the bottom, the Dalits, the "untouchables", are genetically close to the original conquered people
Something like how in Mexico and South America you have upper classes being mostly European ancestry, and the lower classes being mostly native ancestry
There was climate change involved, but the Indus Valley civilization was overrun; the Aryan invasion is denied today of course, for political reasons, but they came from Central Asia, and left due to some kind of climate change. Similar, later movements from Central Asia, but into Europe, are well known.