“The forest is our supermarket,” says Anstice Justin. “We get almost everything from the forests on these islands. It is what we survive on.”

Mr Justin, an anthropologist, has grown up in the Andaman and Nicobar islands straddling India’s east coast. A federally-administered territory, the ecologically-fragile region consists of 836 islands, of which only 38 are inhabited. The Nicobar Islands are a distinct throng of islands in the southern part of the territory, located some 150 km (93 miles) south of the Andaman Islands.

Now Mr Justin watches with trepidation as India plans a multi-billion ‘Hong Kong-like’ advancement assignment on the Great Nicobar Island, one of the largest and most secluded parts of the Nicobar archipelago.

Built on a distribution of 720bn rupees ($9bn or £6bn) and spread over 166 sq km, the assignment includes a transshipment harbour, a power plant, an airport and a recent township, all designed to link the area to crucial global trade routes along the Indian Ocean and the Suez Canal.

Positioned near the Strait of Malacca, one of the busiest shipping lanes in the globe, the assignment promises to boost international trade and tourism – the government reckons that some 650,000 people will be living on the island by the period the assignment is completed in 30 years.

Experts declare the multi-billion schedule is also a part of India’s larger objective to counter China’s growing influence in the region.

But the scheme has sparked alarm among the islanders who terror the setback of their land, population, and way of life, with the assignment threatening to push them to the brink of extinction.

The Andaman and Nicobar Islands are home to some of the most isolated and vulnerable tribes in the globe, with five groups classified as “particularly vulnerable.”

These include the Jarawas, North Sentinelese, Great Andamanese, Onge, and Shompen. While the Jarawas and North Sentinelese remain largely uncontacted, the Shompen – some 400 people – of the Great Nicobar Islands are also at uncertainty of losing their way of life due to external pressures.

A nomadic tribe, most of them live deep inside the forest where they forage for survival – not much is known about their population as very few of them have ever had contact with the outside globe.

“The setback will be especially huge and traumatic for them,” says Mr Justin, who has been documenting the island since 1985.

“Whatever we call advancement in the outside globe is not of yield to them. They have a traditional life of their own.”

Environmentalists declare there are also huge environmental costs of the assignment.

Spread across 921 sq km (355.6 sq miles), around 80% of the Great Nicobar island is covered with rainforests, which are home to more than 1,800 animals and 800 flora species, many of which are endemic.

The federal surroundings ministry has said that only 130 sq km or 14% of the total area of the island will be cleared for the assignment – but that’s still about 964,000 trees. Experts alert the actual number could be much higher.

“The government always claims only a part of the forest will be cleared. But the infrastructure you’re building would navigator to more pollution, which in turn would impact the entire habitat,” says Madhav Gadgil, an ecologist.

The surroundings ministry did not respond to BBC’s request for comment.

But surroundings Minister Bhupendra Yadav in August had said that the assignment “will not disturb or displace” tribespeople and that it had received environmental clearances based on the “rigour of environmental scrutiny and after incorporating consequent safeguards”.

Yet, not everyone is convinced.

Earlier this year, 39 international experts from different fields of social sciences had warned that the advancement assignment would be a “death sentence” for the Shompen as it would ruin their habitat.

It’s a terror that haunts Mr Justin too: “The Shompen people do not have the knowledge or the means to survive in an industrial globe,” he says.

He worries the throng could meet the same fate as the Nicobarese, the biggest tribal throng on the island, which suffered displacement in 2004, when a massive tsunami in the Indian Ocean wiped out their villages.

Over the years, the government made efforts to resettle the people to a different area – but that too came at a worth.

“Most Nicobarese here are now manual labourers and remain in a settlement instead of their ancestral lands,” Mr Justin says. “They have no place to develop crops or keep animals.”

There are fears that the assignment could also expose the Shompen to diseases.

“Uncontacted peoples have little to no immunity to outside diseases like flu and measles which can and do wipe them out – they typically misplace around two thirds of their population after contact,” says Callum Russell, an official at Survival International, a conservation throng.

There are other wider environmental concerns as well, especially about the marine life of the region.

Ecologists alert of the result on the Galathea Bay on the south-eastern side of the island, which has been the nesting place for giant leatherback sea turtles for centuries.

Dr Manish Chandi, a social ecologist, says the assignment is proposed in an area which is home to saltwater crocodiles and the island’s water monitors, fish and avifauna.

A government statement has said the nesting and breeding grounds of these species would not be altered.

But Mr Chandi points out that there are several other species that nest in the area – such as the Leatherback sea turtles, corals and giant robber crabs – which might get displaced.

Even though the assignment would receive 30 long years to complete, people can’t assist but feel anxious about how it will irreversibly alter the delicate settlement of both the surroundings and the lives of the island’s indigenous people.

pursue BBC information India on Instagram, YouTube, Twitter and Facebook.