Under the glaring sun of the Indonesian island of Sulawesi, a young Indonesian woman climbs scaffolding erected on the beach.

Nirmala Syarifuddin is one of a few women working on a large project to re-create a traditional "pinisi" boat, like those used by the Macassan traders who once set sail from her home of modern-day Indonesia.

Across the Banda and Arafura seas, Gumatj elder Timmy Burrawanga sings in language at his family's ancestral Bawaka homeland in north-east Arnhem Land.

In recent months, traditional owners across the Top End of the Northern Territory have expressed alarm about a rise in foreign fishing vessels discovered in their waters.

But Timmy is recalling a songline about oceanic visitors who his ancestors didn't consider "foreign".

Instead, they were trading partners in a vast oceanic highway of Trepang trade, centuries before the arrival of British settlers.

Although colonisation has separated Timmy and Nirmala's cultures over decades, a new documentary contends Yolŋu and Anindilyakwa traditional owners remain inextricably linked with Sulawesi.

Creators hope Wangany Mala, which recently screened in Darwin and at the Ubud Writers Festival in Bali, will help rebuild connections between Aboriginal Australia and Indonesia, to foster mutual respect for the sea country.

Relationship more than transactional trade

A breadth of evidence, from rock paintings of Indonesian ships in Arnhem Land, to photos of First Nations people posing in 19th century South-East Asian photography studios, has demonstrated the pre-colonial ties between the Top End and the islands to its north.

But Wangany Mala's director and producer, Will McCallum, only learned of the trade while working in Asia as an adult.

"It was really crazy to me – and I hadn't learned anything about that growing up," he said.

While travelling to Sulawesi to learn more about the boats they used for trade, he met the young marine scientist Nirmala.

The pair set out to discover more about the relationship between the Macassans, the Yolŋu people of north-east Arnhem Land and the Anindilyakwa people of Groote Eylandt, kickstarting a five-year documentary filmed across Sulawesi, the Gove peninsula and Groote Eylandt.

"This relationship is beyond material, transactional encounters," said co-producer Abdi Karya, translating for Nirmala from Bahasa Indonesia.

The documentary team believes an eerie parallel between Nirmala's own story and an ancient Yolŋu songline about the Macassans, which they discovered late in the process, backs that up.

"There's narratives that are just really exciting and mysterious and fun that just haven't been told," Will said.

Macassan story passed down through Yolŋu songlines

When Will approached north-east Arnhem Land musician Arian Pearson about the project, he jumped on board as a co-producer.

"I think it's a really important part of history for Australia and one that needs to be told," he said.

As a Yolŋu man, Arian has long known his ancestors' stories about the Macassans.

"Yolŋu and Macassans would communicate by writing in the sand … location maps, where to find water, access food.

"I also learnt about the songs and the songlines that were made about them — mainly from the Yirritja people from the south towards Numbulwar down to Groote Eylandt."

But Arian believes colonisation has eroded the once strong maritime relationship between the two countries.

"[Australia] is very protective, but Yolŋu people are very open," he said.

"You have to balance protecting the country from invasive species and diseases, but we need to create a strong relationship with our people from overseas."

Arian hopes the documentary could be a first step towards building respect for Aboriginal waters in Indonesia to help combat a recent spike in illegal fishing.

"We need to establish a better relationship between the Australian government and Indigenous people so we can talk about those issues with Indonesian officials," he said.

Both Arian and Will agree the documentary should be shown in Australian schools as part of an effort to correct colonial narratives of European "discovery" of Australia.

Will is now turning to crowdfunding to show the documentary more widely in Indonesia.

"That's going to enable us to find an audience in Indonesia in particular and enable the producers travel with the film and get that word out more," he said.