There was a particular stillness on the day the Indian Ocean tsunami came to Mo Ku Surin. It was a Sunday morning, 26 December 2004, and the isolated group of islands, a national park 55km from the mainland of southern Thailand, was directly in the path of the wave. On shore, hermit crabs were moving to the forest, eerily absent of its usual bird calls. In the ocean, deep sea fish had been appearing at the surface of the water, while divers reported large numbers of dolphins heading for deeper sea. Hook, a young sea nomad from the Moken tribe who live on Surin, was on a longtail boat checking squid traps.

There was no wind, the ocean was smooth and calm, he says, “like water in a tank. When he saw the white crest of the wave approaching, it was so big he thought it was a ship. “My legs turned to jelly, he recalls. He drove towards it, over and down, a huge drop. When the wave hit the land, it reversed, driving him out to deep water for hours. Many others at sea – including the Thai fishing crews who spent their lives on the water – were caught up in the tsunami, their boats tossed around like playthings. More than 230,000 people are estimated to have been killed by the waves, which reached up to 30m (100ft) high, devastating coastal communities in 14 countries.

Hook’s brother Ngoei was on the beach, near their home on Surin, going to collect honey. He noticed the tide receding and boats stuck in the sand, then returned to the village, a cluster of stilted huts at the water’s edge, to discuss these signs with the elders. Shortly afterwards, his family decided to evacuate. Within minutes, the wave had hit, its loud booming chasing them uphill. His eyes still widen at the memory.

Near the national park headquarters, the tribe’s chief, Salama, was shouting warnings to the park staff and tourists. “This is laboon, he told them, “an ancient thing that has swallowed whole islands before. When the first wave came, Salama faced the sea, asking the spirits to spare his people. His sister Misia, the tribe’s last shaman, was stripped naked by the wave; it took her clothes and jewellery as she clung to a strangler fig tree. The force of that wave and the sight of the next – monstrous, rolling in its wake – told them to run.

Knowledge of the laboon, or “seventh wave, had been passed down for thousands of years through generations of Moken living intimately with the ocean. The Moken – “people immersed in water – learn to swim before they can walk. Ngoei and Hook, both skilled freedivers, had been born on a boat and grown up at sea. They had heard stories of laboon around the fire; when it comes, they had been told, go to the mountains or head to deep water. For the animist Moken, laboon was sent by ancestor spirits to clear out the world’s evils. It would devour everything in its path before all was reborn. “A long time ago, there was a wave so big it covered all but the highest mountain, Tad, a Surin elder, told his family. “Survivors gathered, each race of people, and were sent by a prophet to repopulate the world, and even the men could give birth at that special time. Salama told of the laboon that saw only Moken survive, on a huge platform of vegetation adrift in the sea. There were as many stories of laboon in this oral culture as there were people to tell them.

This tsunami, so devastating to the region, was a relatively small event for the Moken. They all survived. “They were the ones who went out on longtail boats in between waves to pick up survivors in the water and on the rocks, American tourist Mohezin Tejani told the Asia Times. But their villages were swept away. The navy evacuated everyone to shelter at Wat Samakhitham, a Buddhist temple in Kuraburi on the mainland. Life here was alien – noisy roads and speeding traffic replacing beaches, boats and the rhythm of the tides.

As large amounts of aid poured in, there was political fighting among NGOs and the Thai authorities about settling the Moken permanently on the mainland. The monks tasked with distributing aid to the Moken told Salama that his people should stay where they would get boats and other forms of help. If they left, he was warned, they would receive nothing. Salama gathered everyone together and asked what they wanted. They wanted to go home.

The Moken had always been self sufficient. Their language has no words for “want, “take, “mine – money and material goods never held much interest for nomadic people whose traditional wooden kabang boats were designed to show they had nothing to steal. Archaeologists believe these Austronesian people migrated from southern China 4,000 years ago, sailing northwards from the Malay peninsula. They have roamed Burma’s Mergui archipelago and neighbouring islands in Thailand for centuries. Now there are around 4,000 Moken left, 1,000 of them spread around the coast and islands of Thailand.

Until recently many still lived a nomadic life at sea, foraging and freediving to hunt fish to trade for rice, building temporary bamboo huts ashore during the rainy season. But most had given up their wandering lifestyle by the mid-90s, pushed on to land where they are often found surviving among other sea gypsy populations on the margins. The strips of coast and bays they moored in were bought up by developers; crossing the border between Burma and Thailand brought the risk of arrest as the authorities cracked down on immigration. And Moken didn’t have papers.

The Thai government tried to tackle the problem of statelessness after the tsunami – about 200 people who could prove they were born in the country got full identification. Tad and his wife Sabai were unable to establish their birthplace and received identity cards that restricted movement – a prison sentence for nomadic people. The couple held out until 2009, living afloat with their family. But life had become more lonely and less free – no more flotillas, no company for their three boys. They were the very last nomads.

They now live on Surin along with the the 270 or so evacuated Moken who left the mainland to return to the islands immediately after the tsumami. They were followed by an influx of aid workers, tourists and journalists. Film crews came, stage managing sacred spiritual ceremonies, with loincloths for the villagers to wear in place of their usual clothes. A Dutch production company took Salama and other villagers off to the mainland to take part in a reality television show, The Mystery of Rang Nok – suddenly the elder found himself in the baffling position of giving survival tips to young Europeans competing in a “sea nomad game. Christians asked the Moken to convert. NGOs galvanised many into action on development projects, then pulled out halfway through due to the challenging conditions. Hopes were raised and shattered.

After the tsunami, the park authorities relocated the two separate villages into one bay, Au Bon Yai, where they are today, but the Moken were not allowed to follow important cultural traditions in rebuilding. They had always sited their huts with their stilts in the water – this was symbolically important, living between land and sea like the turtles they consider to be mythical relatives; but it also had practical purposes, the salt water washing away their waste. The new huts were crowded together further back, in regimented lines close to the jungle. The authorities’ fear of tsunami had taken precedence over Moken beliefs that spirits reside in the forest.

In time aid money enabled some improvements to the overcrowded settlement. The construction of a water system, public toilets and the introduction of solar panels and electricity would give the Moken a “reason to stay here and not wander away again, the director of the provincial electricity authority put it at the time, as though discussing wayward children. A foundation linked to Thai princess Maha Chakri Sirindhorn paid for a new school and teachers.

But most charities had given little thought beyond financing construction. The nomadic Moken were not used to living as a large community. There were no systems in place to share responsibility for public facilities, and there was a lack of knowledge in dealing with them. The sudden availability of piped water led to greater use and shortages; the toilets, built cheaply and quickly, were inadequate. The resulting levels of waste and stagnant water created a breeding ground for mosquitoes, flies, rats and cockroaches; combined with overcrowding this led to an increase in diseases such as malaria, dysentery and tuberculosis.

The majority of charities also failed to tackle the educational needs that would help the Moken adapt to their new environment and they were left vulnerable to marketing and misinformation. Some mothers took to nursing their babies with condensed milk, children were drinking coffee like it was Ovaltine. As they began to consume more refined sugars, saturated fat, salt and alcohol, there was a rise in the diseases of affluence – diabetes, heart disease, cancer, high blood pressure – but without access to the healthcare needed to treat them. Like so many tribal people, the Moken had been exposed to the vagaries of modern life with few of the benefits; they were left with the worst of both worlds.

And they already had problems. When the islands were granted marine park status in 1981, crucial aspects of the Moken’s culture were in effect criminalised. The intervention of Thailand’s late Queen Mother had prevented their eviction from their ancestral homeland, but they had no legal protection or rights to stay. In the mid-80s, park staff had arrived, building on Moken burial grounds. Wielding AK47s, they moved the pacifist Moken from one “zone to another, aggressively imposing “conservation on people who had lived with the smallest of footprints for centuries, their movements were restricted, they were no longer allowed to hunt for fish to trade. The Moken watched trawlers empty the seas while they risked arrest for spearing a single fish. The logging ban prohibited their felling of a tree to make kabangs: the boats, and the skills to make them are now disappearing along with the elders. The post-tsunami aid and development accelerated the erosion of Moken culture. And then mass tourism came.

Now each day in high season longtail boats full of tourists are deposited at the Moken’s village. Various shades of white and red flesh spill out of beach shorts and bikinis as visitors wander, cameras snapping at mothers breastfeeding their babies, zooming in on the lined faces of elders. Life continues amid the indignity: youngsters shout and race for falling mangoes. Some villagers try to sell handicrafts; when he can afford the 200 baht (£3.90) for a solar battery, Tad spends evenings crafting miniature boats. But tourists in swimwear don’t carry much cash. Today’s visitors have brought money though. A Thai couple have taken a group of children on to the beach and are handing out baht.

Further along the bay, the strains of children singing drift into Tad and Sabai’s hut from school. In the classroom, their youngest son hesitantly begins his English, “Good morning, my name is Bau … How are you? The school was rarely open at first – Thai teachers spent more time on the mainland. It is now operating full time with 120 students. This transformation is because of Khaeng, Hook and Ngoei’s younger sister, and the first ever Moken graduate.

Khaeng almost didn’t make it beyond crawling age. Her parents, Jao and Juri, were on the beach when Jao says the spirits came to him with a warning. He ran to find his little girl already green, headfirst in the water, tiny feet peeking out, belly full of sea. The elders took over, ran with her over their shoulders to expel the water; Juri threw feathers to ward off evil spirits. Ancient wisdom saved her that day, but her parents valued modern education too.

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