Aboriginal activist and community leader Noel Pearson has called on Australians to unite by voting 'yes' in the upcoming referendum on an Indigenous voice to parliament.

"Yes' will recognise Indigenous people in the constitution but the bigger project is one of understanding who Australian people are," he said in a speech at the Garma festival in northeast Arnhem Land in the Northern Territory on Saturday.

"What's our history, where do we come from, who we are in the present and what do we want to leave to our children?"

Mr Pearson said a successful referendum would entwine three cultural histories together - Indigenous, British and multicultural.

"Australia is going to put behind it the idea of settler versus natives when it recognises Indigenous people as Australian," he said.

"This vote in the referendum is the most important, what we do now is absolutely momentous."

Mr Pearson also laid down the challenge to Garma attendees to take a message of strength and hope about the referendum when they go back home.

"We're going to love them on the beaches, love them at every front door, on football pitches, every railway station, we're going to leave no stone unturned," he said.

"We're going to add a little bit of soul to our founding document.

"It's a beautiful document, the constitution - it's like the rules of cricket and about that compelling - but all of a sudden we're going to have a new provision and when children read this and think 'Oh, this is what Australia is'."

Prime Minister Anthony Albanese flagged the referendum will likely be held in October or November this year.

Mr Albanese reiterated he planned to set a date for the historic vote after the football grand finals were held in September.

"Obviously when we get into December, you are into the rainy season, so that gets knocked out," he told ABC television on Saturday.

"September, it could be held then, except we have the footy finals.

"So we will make an announcement soon, we will talk through with the Australian Electoral Commission and make sure it's an appropriate date that doesn't clash with other events."

The Garma festival is the nation's biggest Indigenous cultural gathering and being hosted by the Yothu Yindi Foundation on Gumatj country. This is its 23rd year.

It festival holds a deep resonance for former Labor senator and an Olympic gold medallist Nova Peris and her daughter Destiny.

"Yothu Yindi means mother and child," Peris said.

"Garma is two-way learning, bringing all the knowledge together - it's not just Aboriginal people continuing their cultural responsibility, it's actually showcasing to the rest of Australia how rich our culture is."

Peris agreed with Mr Albanese's previous comments that the festival was an opportunity to discuss the upcoming referendum on an Indigenous voice.

"I think about the ignorance, about our non-existence in this country – terra nullius," Peris said.

"Every non-Indigenous person who comes up here has to walk away with a sense of wow, Aboriginal people, we thrive, we co-exist, we're welcoming and irrespective of the s****y past that this country has thrown at us, we still open our arms and try to educate the rest of the country."

She believes a 'yes' vote in the referendum will help address inequality.

"It's 2023 and if you think that this country popped up out from the water in 1788 with the Union Jack being planted declaring terra nullius you need to go back to the hole that you came from," Peris said.

"There are two histories here, there is 1788 and there is now.

"You can't change anything that happened in between but in order to progress this country, to unite this country, there needs to be an acknowledgement of our existence."

Rudi Maxwell - AAP