Recent debate in the United States over the legacy of slavery has reignited discussions about Australia's own dark past.

Starting from the 1860s, tens of thousands of Pacific Islanders were taken to Australia to work on plantations in Queensland, often by force or trickery.

Unmarked mass graves full of labourers who died on those plantations are still being uncovered today.

Now their descendants, the Australian South Sea Islander community, are calling for their history to be properly recognised.

What was 'blackbirding'?

While there is evidence that some of the 62,000 people sent to Australia came willingly, and signed contracts to work on the plantations, many others were lured or taken forcibly onto the boats.

This practice is what's known as blackbirding.

Many workers did not know what they were signing up for. ( State Library of Queensland )

The majority of the labourers were men, but women and children were also taken.

Most were originally from Vanuatu and the Solomon Islands, however workers were also "recruited" from the Loyalty Islands (part of New Caledonia), Papua New Guinea, Tuvalu, Kiribati and Fiji.

The first of Queensland's blackbirded men arrived in Moreton Bay on the ship Don Juan in 1863, and worked on a cotton plantation.

While some of those contracted may not have understood what they were signing up for the first time they came to Australia, many returned multiple times by choice.

Emelda Davis, president of the organisation Australian South Sea Islanders Port Jackson, said her grandfather was kidnapped from the island of Tanna in Vanuatu as a 12-year-old boy.

"He was put on a boat with no say — couldn't say goodbye to his family — and sent to Australia to work on the Queensland sugar farms," she said.

"America had already fought a civil war over the end of slavery at this point and here in the Pacific it was just taking off."

Was it slavery?

Well, the fact that the men were paid makes it difficult to classify them as slaves but it's worth noting the wages paid were well below what European workers earned.

First-year workers received a standard pay rate of six pounds per annum, and that rate was fixed for 40 years despite wage inflation elsewhere in Queensland.

Likewise, as the men had signed contracts, they were technically indentured labourers.

The British Empire had ended slavery by the time the Don Juan arrived in Queensland.

However this legal definition does not mean the men didn't experience "slave-like conditions."

"After slavery was abolished the British practitioners asked themselves 'how can we get the same labour we used to get,' so they used the indentured system," said Professor Clive Moore, a leading researcher on South Sea Islander history at University of Queensland.

"Whether you call them slaves or not, they definitely worked in slave-like conditions. It was often horrific."

Ms Davis said this was reflected in her family's oral history of what happened to her grandfather.

"I was told that once they were here, they were unable to speak their mother language, they were punished in terms of corporal punishment," she said.

"They were segregated from wider society just like African Americans were in the US."

Most labourers who died on the plantations were buried in unmarked graves. ( State Library of Queensland )

The labourers also suffered a high death rate.

Around 30 per cent of arrivals died at the plantations due to exposure to European diseases, malnutrition and mistreatment.

Most were buried in mass unmarked graves, some of which are still being uncovered today.

When did it stop?

The indentured labour of Pacific islander workers came to an end during the advent of another particularly uncomfortable era in Australian history.

The Pacific Island Labourers Act of 1901 ordered the mass deportation of most of the 10,000 or so indentured labourers in the country.

The legislation was part of a package of reforms that later became known as the White Australia Policy.

Under the Act, the only islanders allowed to stay in Australia were those who arrived before September 1 1879, worked in ships' crews or received an exemption.

This amounted to around 700 people all up.

The labourers tried very hard to challenge the Act — an incredible feat at the time — and even sent a petition to King Edward VII, signed by 3,000 islanders.

Only about 2,500 islanders avoided deportation. ( State Library of Queensland )

Opposition to the law resulted in the government widening the exemption categories, however the deportations still went ahead, starting from 1906 and continuing until mid-1908.

The way the Government funded the mass deportation was, by modern standards, very disturbing.

When workers died their wages were put into a fund used to send trade goods back to their islands, as compensation for their deaths.

This only ever happened in around 16 per cent of cases, with the Queensland Government absorbing the rest.

The Queensland Government gave what remained of that money to the Commonwealth to pay for the deportations.

"The money of the dead paid for the deportation of the living," Professor Moore said.

Only about 2,500 islanders avoided deportation, and their descendants are now known as Australia's South Sea Islander community.

What's happened since?

Well, this really depends on who you ask.

In 1994, the Commonwealth Government recognised South Sea Islanders as a distinct cultural group and thanked them for their services to Australia's economy.

Queensland followed suit and formally recognised the community in July 2000, along with New South Wales in 2013.

Professor Moore said while this was promising at the time, precious little had been done since.

'This history is all of ours ... we really need leaders to own up to it.' ( State Library of Queensland )

"Australia has in the past few decades begun to really acknowledge Aboriginal and Torres Strait Islanders, but too often the South Sea Islanders are forgotten," he said.

"Even now there is chatter about contemporary slavery, what about our own slave past ... South Sea Islanders continue to suffer because of it."

Ms Davis has devoted her working life to leading the call for the South Sea Islander community to have their history recognised in Australia.

"This history is all of ours and for us to move forward as a nation we really need leaders to own up to it, acknowledge it and then come to the table with us, work with our leadership groups to help right these wrongs."