The remains of Mungo Man, the oldest known human being in Australia, are at last being returned to their ancestral homeland in remote western NSW, 42,000 years after he walked the land.

Researcher Jim Bowler first discovered remains on the shore of the ancient and long-dry Lake Mungo, 750 kilometres west of Sydney, in 1968.

He and an Australian National University team initially unearthed the remains of Mungo Lady, who'd been cremated then buried more than 40,000 years ago.

Then, in 1974, Dr Bowler discovered further ochre-adorned remains from a similar period. They become known as Mungo Man.

In 1992, after decades of campaigning by local communities, the Lady's remains were returned to Lake Mungo.

But it's taken another 25 years for a hearse carrying Mungo Man, along with the remains of 100 other ice-age people removed from the land, to make the long journey from Canberra back to the lake.

Mungo Man will be repatriated at a ceremony on Friday with an indigenous music festival to follow in Mildura on the weekend.

ANU historian and National Museum indigenous history director Ann McGrath told AAP the discoveries changed the way historians viewed Aboriginal and human history.

"In the 19th century it was thought Aboriginal people had been here between 2000 to 4000 years so little archaeological work was done," she told AAP this week.

"To find people had been here 40,000 years was mind-boggling. Scientists had never even thought of it.

"There were Neanderthals still in Europe. Many thought homo sapiens were yet to exist (but) there's some growing evidence that megafauna was coexisting with Aboriginal people."

The remains were transported to Canberra following their excavation where they were held by both the ANU and then the National Museum for study by scientists.

The removal of Mungo Lady, Mungo Man and the 100 others created a sense of anxiety in local Aboriginal communities, Professor McGrath said.

"The Aboriginal people don't act like it was so long ago ... it's like they died yesterday."

Some Aboriginal people have campaigned for decades to have the remains returned.

"Australian history did not begin with Captain Cook, there was an astonishing civilisation and history already," Prof McGrath said.