The Indigenous people of Australia have lived there for a very, very long time, but just how long has been a source of contention.

Now there's perhaps a more concrete answer. New evidence published in the journal Naturepoints to humans inhabiting Australia for 65,000 years -- much earlier than the 47,000 years estimated by some archaeologists.

It's the result of more than 10,000 artefacts discovered at the lowest layer of a site called the Madjedbebe rock shelter, which uncovers some of the complex behaviour of the earliest modern humans.

"The site contains the oldest ground-edge stone axe technology in the world, the oldest known seed-grinding tools in Australia and evidence of finely made stone points which may have served as spear tips," according to Associate Professor Chris Clarkson from the University of Queensland in a statement.

"Most striking of all, in a region known for its spectacular rock art, are the huge quantities of ground ochre and evidence of ochre processing found at the site, from the older layer continuing through to the present.

Since the 1970s, archaeologists have excavated the Madjedbebe site four times, most recently in 2012 and 2015.

It's located on the lands belonging to the Mirarr people, in an area surrounded by Kakadu national park in the Northern Territory. The Mirarr reached a landmark agreement with researchers to dig up the site.

Dating of these artefacts by Professor Zenobia Jacobs from the University of Wollongong also reveals the earliest Indigenous Australians lived alongside an extinct species of giant animals.

The discovery could also challenge what is understood about the dispersal of modern humans out of Africa, to what is now Southeast Asia.

It's thought that people crossed over from Southeast Asia to Australia at a time when there were lower sea levels and a shorter distance between the two countries.

Located within an area earmarked for uranium mining, Madjedbebe has been at the centre of archaeological debate -- but the latest findings also accentuate how important it is to protect the site.

"This study confirms the sophistication of the Australian Aboriginal toolkit and underscores the universal importance of the Jabiluka area," Justin O'Brien, CEO of Gundjeihmi Aboriginal Corporation, said in a statement.

"These findings reinforce the need for the highest level of conservation and protection for this site."