‘The Indians don’t speak our language, don’t have money or culture. They’re native peoples. How did they end up with 13 per cent of Brazil’s territory?’ Jair Bolsonaro said to an audience in Mato Grosso do Sul in 2015, before becoming Brazil’s thirty-eighth president. At other times, he has said that the demarcation of indigenous territories is an obstacle to development and that the Amazon basin should be opened up for economic exploitation. Back in the 1990s he went further, lamenting in the Correio Braziliense newspaper: ‘It’s a shame that the Brazilian cavalry was not as efficient as the American, which exterminated the Indians.’

At this frankly apocalyptic moment for indigenous rights in Brazil, John Hemming’s People of the Rainforest is a timely work. The book tells the extraordinary story of the Villas Boas brothers – Orlando, Claudio and Leonardo – who in the 1940s and 1950s explored vast areas in and around the Xingu headwaters, in the northeast of the state of Mato Grosso, to the south of the Amazon river. Through painstaking contacts with indigenous groups scattered across an area the size of England and Wales, and through equally intricate political manoeuvring, by the 1960s the brothers had secured the establishment of an enormous protected area: the Xingu Indigenous Park.

To this day, satellite images bear testimony to the long-term success of this project: the biscuit-coloured plots of cleared forest stop – for now – at the boundaries of the park, which remains largely intact; inside its frontiers is a huge expanse of bottle-green semi-wilderness, home to diverse indigenous groups that have recovered from a state of near-extinction.

As Hemming writes, in the 1940s Brazil was in a sense where the USA had been a hundred years before: a country whose eastern seaboard had long been settled and intensively farmed, but whose immense interior lay relatively untouched by colonialists. But unlike the USA’s open plains, much of the Brazilian interior – particularly the north – was covered in dense tropical forest, limiting easy access. While the arterial routes of the Amazon basin’s river system were well known by the 1940s, few explorers had penetrated far into the forested regions in between.

In 1943, the Villas Boas brothers joined the ‘March to the West’ expedition, one of a series of nationalistic efforts launched by President Getúlio Vargas to open up the ‘forested heart of the nation’. The brothers cut unlikely pioneer figures. Middle-class city boys from São Paulo with a fascination for exploration, they joined a group of tough, illiterate frontiersmen on trips that would test their physical stamina to the limits.

The expedition was a very mid-20th-century affair. The brothers and their team’s initial, arduous task was to cut trails through the undergrowth, moving first through the cerrado (grasslands studded with gnarled shrubs) and then, further north, penetrating the tropical forests. At intervals they would establish posts and make clearings for airfields so that the Brazilian air force could freight in supplies for the next leg of the journey. In this manner, they inched their way westwards, tormented by clouds of blackflies and mosquitoes as they cut their way through a forested corridor cladding the mighty Xingu river, a tributary of the Amazon. (The Xingu had been difficult to ascend by boat because of the dense forest surrounding it and a series of rapids and waterfalls that effectively blocked riverine traffic on the first third of its 1,640 kilometres.) The airstrip system was crucial for the evolution of the park. It meant that access could be controlled (something that would have never been assured if roads had been built). A steady supply of food, medicines, doctors and other specialists could also be airlifted in on the Douglas C-47 military transport planes that used the posts as way stations en route to Manaus and Miami.

The Villas Boas brothers were sensitive to the plight of the indigenous groups they encountered, from the first – often tense – contacts to the subsequent management of the relationship between them and their Brazilian counterparts. Unlike the integrationalist ethos favoured by Cândido Rondon, the great explorer who had opened up areas to the west of the Xingu in the 1910s, the Villas Boas brothers’ philosophy was one of slow and managed change, allowing indigenous groups to adapt to Brazilian society at their own pace, while maintaining their dignity and cultural integrity – an approach requiring great skill, patience and humility.

While united in their aims, the brothers come across in Hemming’s account as distinctly different characters. The oldest, Orlando, was an extrovert and a natural leader. By contrast, the middle brother, Claudio, was ‘quietly steadfast, cerebral, and doggedly patient’ and the youngest, Leonardo, ‘tough and macho, but rather introverted’. During downtimes, Orlando would smoke cigarettes and read popular fiction, magazines and photographic novellas. Claudio was more ascetic, staying in a bare hut, listening to Stravinsky and Beethoven, and reading Hegel, Lévi-Strauss and Freud.

But in a sense this book is not so much about the brothers themselves as about the peoples they tried to help. What emerged from decades of exploration and interaction with indigenous groups was a series of posts that operated as assistance points for diverse peoples, some from the immediate surroundings, some from further afield and some, more controversially, removed wholesale from distant frontier zones.

Bringing former enemy groups together and ending blood feuds, the brothers ushered in a ‘Pax Xinguana’, while also giving indigenous groups the space and medical support they required to rebuild their populations, which had been decimated by outbreaks of measles and flu. Some have questioned the Villas Boas brothers’ overall approach – indeed, more recently there has been a tendency to eschew any contact with isolated indigenous groups where possible. But without them, the Xingu could well have been overrun, with disastrous consequences for its inhabitants, just as has happened in many other parts of the Brazilian north.

This is a short book, but it is packed with detail and fascinating anecdotes, a testimony to Hemming’s long association with the region and his friendship with the brothers. After reading such rich evocations of indigenous peoples’ cultural and emotional lives and their struggles to survive the onslaught of colonialists, the ill-informed views of President Bolsonaro look even more extreme and dangerous.