In the 21st century, globalisation has brought the planet's disparate populations and cultures closer than ever before, but there are still places — and people — who remain largely untouched by the outside world.
One of those remaining "lost" civilisations was thrust into the spotlight this week when American tourist and missionary John Allen Chau was reportedly killed by a flurry of arrows launched by an isolated tribe on a remote island in the Indian Ocean.
Those thought to be responsible, the Sentinelese tribe, live cut off from the outside world on an island located in India's remote Andaman and Nicobar chain which is off-limits to visitors, reports news.com.au.
Because contact with the tribe is forbidden, Mr Chau's killers will not be prosecuted for his death, according to local authorities. However, seven local fishermen were arrested for taking the American to the restricted island.
Just like the world's hidden populations, stories like this are increasingly rare.
But the Sentinelese tribe are not completely unique in their isolation. In fact there are still considered to be around 100 uncontacted tribes living completely shut off from the outside world.
THE SENTINELESE TRIBE
Very little is actually known about the indigenous Sentinelese people who occupy the small island in the Bay of Bengal in India.
The island — which is just 60 square kilometres and sits 1200km from the Indian mainland — has belonged to India since 1947 but is recognised as a sovereign state.
Rough estimates have put the Sentinelese population anywhere between 50 and 150 people. They live a hunter gatherer lifestyle on the heavily forested island and are said to have their own entirely unique language unintelligible to outsiders.
Scholars believe the Sentinelese migrated from Africa roughly 50,000 years ago, but most details of their lives remain completely unknown.
Overflight footage and satellite photos reveal no sign of agriculture. They do use metal, but it comes only from the few shipwrecks along their coast.
As this week's tragic events show, they really don't like visitors. An attempt by the Indian government to formally contact the Sentinelese tribe in 1996 was rebuffed. Ever since then they shoot arrows at any boat that comes too close to their shores.
In 2006, members of the tribe killed two poachers who had been illegally fishing in the waters surrounding their home island after their boat drifted ashore, according to London-based watchdog group Survival International.
"Contact must never be imposed on tribes who don't want it," the group said on Friday. "Their neighbours, the Jarawa, have been treated like safari animals by tourists for years."
Out of respect for the tribe's clear wishes to be left alone, the Indian Government has made it illegal to sail within five kilometres of the island and strongly protect them.
THE MOXIHATETEMA TRIBE
In 2016, a plane flying over the Amazon rainforest in Brazil captured photos of the peoples of the lost Moxihatetema tribe.
The highly insular group has consistently spurned contact with the outside world and it's believed that they even keep to themselves among the other indigenous communities in the area known as the Yanomami — a collection of about 35,000 indigenous people who live in some 200 to 250 villages in the region of the Amazon rainforest.
Despite being surrounded by illegal mining groups, the indigenous tribe is remarkably traditional, appearing to have no industrialised possessions, according to those who have seen them from afar.
"We know that there are around 100 uncontacted tribes around the world. Most of them are in the Amazon, but there are others elsewhere in South America, and in Asia," Fiona Watson, the former Campaigns Director at Survival International, told news.com.au in 2016.
"There is nothing inevitable about the annihilation of uncontacted tribes. Where their lands are protected, they thrive," she said at the time.
But illegal logging operations and miners, often referred to as Wildcat miners, represent one of the most pressing threats to the uncontacted peoples of the rainforest as the outside world continues to encroach on their environment in the hunt for natural resources.
JAVARI RIVER VALLEY TRIBES
In August, the Brazilian government body FUNAI, which describes itself as a protection agency for Indian interests and their culture, shared drone footage and photos taken in 2017 of an uncontacted tribe in the Javari Valley.
The pictures showed a thatched hut in the indigenous territory, canoes and tools of indigenous tribes.
The Javari River region is home to eight contacted tribes, and 11 confirmed isolated tribes, according to FUNAI.
The group was originally founded in 1910 by Brazilian marshal and explorer Candido Rondon, famous for his philosophy on interacting with tribes in the Amazon: "Die if necessary, but never kill."
Little is known about the uncontacted peoples in the region and efforts to find out more are discouraged these days. Overflights reveal they both hunt and cultivate their food. It's also known they have acquired metal goods through trade.
The fate of one of these tribes — the Matis — compelled the Brazilian government to change its policy of enforced contact.
Within weeks of the first visit by officials, disease decimated three entire villages. In the face of such a disaster, Brazil ordered an end to all future such efforts.
Aside from the threat of disease, the risk to these remote tribespeople comes from ever closer mining and logging operations.
THE LITTLE KNOWN NEW GUINEA
Little is known about the uncontracted tribes of New Guinea. West Papua is known to have about 312 tribes. And some of these intermediate tribes — those that have made contact in the past century — still tell tales of other remote groups living further up in the remote highlands.
Contacting these tribes has not been easy: Michael Rockefeller, the son of vice-president of the United States Nelson Rockefeller, vanished while filming the Asmat people in New Guinea.
One of the largest Papua highlands ethnic groups, the 25,000 or so Dani, have managed to maintain their culture despite increased interaction with the outside world.
This may be because some of its communities are more remote than others: first contacted in 1909, one village was discovered from the air in 1938.
These tribes crop sweet potato, banana and cassava. They also herd pigs.
But they also follow some complex cultural practices — including penis gourds, smoke-mummification of elders and chopping off fingers to remember those killed in warfare.
Proud of their traditions, they also regard modern metal tools to be inferior to their own stone axes and blades — both in terms of performance and maintenance.
'NOT VIABLE IN THE LONG TERM'
"People have this romanticised view that isolated tribes have chosen to keep away from the modern, evil world," anthropologist Kim Hill told the BBC in 2014. "There is no such thing as a group that remains in isolation because they think it's cool to not have contact with anyone else on the planet."
The following year, Professor Hill and Professor Robert Walker published an editorial in Science magazine in 2015, calling for organised efforts to bring all "lost" tribes in contact with surrounding societies.
They argued these people's cultures were no longer sustainable, and it would be more humane to integrate them into our own in the face of uncontrolled contact from miners, loggers, traffickers and thieves.
"Isolated populations are not viable in the long term," they wrote, adding "well-organised contacts are today both humane and ethical. We know that soon after peaceful contact with the outside world, surviving indigenous populations rebound quickly from population crashes."
They argue initial contact should be made by anthropologists, who then stay on site to monitor the community's health — and call for help should an epidemic break out.
But other anthropologists argue this simply repeats the mistakes of the past, when missionaries and officials were encouraged to engage in peaceful contact with indigenous peoples.
They offered gifts of metal, medicines, glass — and bibles. But they also brought viruses and bacteria, killing the very people they intended to "save".
As a result, Brazil — along with India and Indonesia — are attempting to enforce a policy of protecting uncontracted tribes' lands and allowing them to live in isolation.