Through a dense and remote pocket of the Amazon rainforest, once riven only by a network of rivers and tributaries, cleaves a part-dirt, part-asphalt road like a muddy laceration on the landscape.
Built under the military dictatorship in the early 1970s, the Transamazonica highway was billed as Brazil's "road to progress", opening up the north of the country to the depths of the jungle. But in cutting through the land inhabited by the Tenharim people who had previously lived off the Marmelos tributary, instead it opened like a wound the conflict between native Indians and the non-indigenous.
Four decades on, and a "climate of war" has erupted, with mob violence leaving indigenous buildings torched in a series of Christmas attacks on the Indian reserve that surrounds the road.
Amateur video footage shows buildings ablaze as an estimated 3,000 people descended on the land from the nearby town of Humaita, 435 miles from the Amazonian capital of Manaus. Women, children and the sick were among the 140 forced to seek refuge at a nearby army base after the worst confrontations on Christmas Day.
The protest had ostensibly been sparked by the disappearance of three non-indigenous men who went missing when crossing the Tenharim reserve on the Transamazonica on 16 December. The Tenharim tribe was accused of kidnapping the men out of revenge for the death of their chief, Ivan Tenharim, 45, two weeks earlier.
Video: Tribal leader Magarida Tenharim defends her people
Video credit: Midia NINJA
According to police, the native leader was killed in a motorcycle accident, although his community believe he was assassinated. But much of the anger and violence from residents has been directed at the toll booths set up by the Tenharim people on the Transamazonica as a way of recouping compensation for the environmental damage and loss of land.
Protesters attacked one illegal toll booth, which had been collecting taxes for seven years, with axes, machetes and fire, according to police.
Logger Elias Trepak, 60, said the Tenharim road toll was the root of the conflict. "We have two Brazils - one, in which we live; the other is a 'little Brazil' the government reserves for Indians," he said.
The government's National Indian Foundation (Funai), which was also among the targets, described the violence as "unjustified and illegal" after its bases, boats and cars were also destroyed.
"Since the construction of the Transamazonica in 1972, no alternative was created to minimise the impact on the Tenharim land," a spokesman for Funai said.
"So the indigenous, by their own initiative, implemented a toll as an environmental compensation and as an alternative that funds activities that benefit those people.
"In May last year Funai, in meeting with Tenharim leaders and representatives of the federal prosecutor, discussed the possibility of a corrective environmental licence, to offset, mitigate and compensate the Tenharim people for the impact caused by the construction of the Transamazonica, which intersects Indian land.
Funai is currently completing a study of the impact of the highway. "Funai sympathises with the indigenous and non-indigenous families looking for information about the case while rejecting any type of protest that incites hatred or violence."
Meanwhile, five village chiefs agreed to suspend the toll while police searched for the missing men, named as Professor Stef Pinheiro de Souza, businessman Luciano da Conceição Ferreira Freire, and Aldeney Ribeiro Salvador, a manager with the state-owned firm Electrobras.
Four members of the Military Police claimed that they saw Indians pushing a car near the village of Tabocal, some 280 miles from Humaita, the news website Amazonia Real reported. On Friday a charred Gol car matching the description of the car used by the three men was found by search teams within the reserve.
The Tenharim people deny that they had any involvement. "They accused us of this nonsense without evidence," tribal leader Margarida Tenharim told the independent journalist collaborative Midia Ninja. "They say we killed them and that they are here but they don't prove it. They don't prove it and they won't prove it. They just accuse, accuse, accuse.
"We feel the pain of their families. Today, we do not fight with weapons. We want our rights like any other human being. We have been waiting for years and no one compensates us."
The native leader suggested the men may have been killed and their bodies dumped on the reserve to implicate the indigenous community that has long defended their rights to the land in the face of exploration and development.
"I didn't study, I don't know how to speak well or write, but I know from my origins, in my mind, from my education that this is not how it is done," Margarida added. "We don't take the lives of others like animals. I feel as a mother, as an Indian, just as the whites feel, so we don't do that."
Since the Tenharim returned to their land on 30 December with protection from the police, the National Force and Funai, the Mayor of Humaita, José Cidinei Lobo do Nascimento, has asked for army protection after the clashes left his community without aid, medical supplies and support.
In the wake of the unrest, police also redoubled efforts to search for the missing men. Stefanon Pinheiro de Souza, brother of the missing teacher, said he believed that Professor Pinheiro was alive and being held in the Tenharims' village. "We are sure that it was the Indians who took them. But we want a response from the authorities. We cannot wait," he added.
The Tenharim people include three indigenous groups, who live off the Madeira river and its tributaries in the south of Amazonas. Those belonging to the Tenharim Marmelos tribe dropped in number when they moved to the edge of the highway, leaving just 300 in 1994. Around 400 are believed to live in the village now.
Egydio Schwade, founder of the Indigenous Missionary Council, blamed the lack of attention from the authorities for the conflict involving the Tenharim people, who were going through a period of reorganisation since their land was explored during the building of the Trans- amazonica.
"This case is very serious because of the economic interests," he told news website D24AM.
"That land is coveted because of ore, and I also believe that large landowners want to invade that area.
"The best way to contain the conflict is by direct intervention of the federal prosecutor because the country does not have, in current conditions, the credit nor the morals to protect these people, as there has also been a lack of political will to resolve indigenous issues."