By Guy De Launey
BBC News, Phnom Penh
Life for the tribes of Ratanakkiri has been much the same for centuries.
The itinerant life of the tribes in Ratanakkiri is at risk
People in this north-eastern corner of Cambodia farm the land collectively.
First thing in the morning, they make their way to the fields along the red clay paths, many of them puffing on gigantic, conical, hand-rolled cigarettes.
Traditionally, they up sticks and move their village every few years.
There are no fences. The land belongs to all and they say: "The forest is our market."
There are eight different ethnic groups living in Ratanakkiri. They have their own languages, and most of them are followers of animism, worshipping spirits in the trees, rocks and rivers that surround them.
Several years ago, the government recognised that the indigenous people collectively owned the land - and should do so in perpetuity.
But the registration process has been painfully slow, leaving the way open for land-grabbers.
Village chief Bran Godreng says sacred spirits have been disturbed
Their problem is indicative of a wider issue affecting many parts of Cambodia.
The UN special rapporteur on adequate housing, Miloon Kothari, recently acknowledged that rich and powerful interests were taking land in the country, leaving thousands of people dispossessed.
These land-grabbers can be powerful opponents. As a bunch of local men gathered on the porch of a wooden house in Ratanakkiri's O'Yadaw district, they chewed over the problems they faced.
"Brokers connected to rich people come here to convince people to sell land," one of them told me.
"And because people need money, some of them agree. But then the land is fenced off - and that makes our lives very hard."
"We can't protect our forests and land by ourselves," another said. "We need government involvement. But local officials have been involved in selling land too."
The result of one such deal can be seen just a few miles down the road. A swathe of land has been fenced off, and workmen are setting up a rubber plantation.
The locals said a village chief connived with district officials to sell the land illegally to some well-connected people from Phnom Penh.
They persuaded the villagers to agree to the deal by throwing a party, getting them drunk, and producing documents for them to thumb-print.
The government's own dealings have not sent out the best signals. Despite a moratorium on logging, the wood for the new National Assembly building will come from freshly felled trees in Ratanakkiri. Workers have already marked the trees to be cut.
A Forestry Administration official at the site explained that the National Assembly project would only take carefully selected trees, and would be strictly limited in its scope.
But he admitted that the very presence of the concession had encouraged other, illegal loggers - who also claimed to be taking wood for the assembly building.
Local village chief Bran Godreng was unimpressed. He said the loggers were disturbing a spirit forest sacred to the Kreung people, and complained that no one had asked for permission or shown him any official paperwork.
Villagers have staged protests, and attempted to block the loggers' vehicles, but they have little chance of reversing the decision.
People in the area may be forced to turn to tourism for a living
Traditional ways of life in Ratanakkiri are likely to face an increasing number of challenges in the next few years.
Millions of dollars will be spent on building new roads - and the red dirt strip and wooden hut at Ratanakkiri airport will soon be replaced by a runway and terminal building capable of handling thousands of tourists a week.
Even the Asian Development Bank, who is funding the improvements, is concerned about the effects of opening up Ratanakkiri to the world.
It is examining the possibility that human traffickers could use the new roads linking the province to Vietnam. There are also fears that sex tourism could increase.
The main problem facing the tribes of Ratanakkiri, however, is an erosion of their culture.
The young people growing up near the stunningly beautiful volcanic lake Yeak Laom are facing a future of working as tourist guides, as they gradually lose their traditional lands.
A place they once used as a burial ground is now another rubber plantation, owned by outsiders.
The modern world has arrived in Ratanakkiri, but not always to the benefit of its oldest inhabitants.