For generations, the indigenous Bunong were famous as the elephant keepers and masters of the forests in eastern Cambodia. They called the fertile, rolling hills of their ancestral homeland "meh ne," or mother. From its rich red soil, they harvested rice, pumpkins and bananas. From the forests, they gathered honey, resin and medicinal plants. Under the leafy canopies, they buried their dead and worshipped spirits.

That changed in 2008, when without warning, bulldozers made way for rubber plantations the government granted to a European-Cambodian joint venture in poor, rural Mondulkiri province. Such economic land concessions were meant to promote development, but for 800 Bunong families, the long-term leases have brought mostly hardship and loss.

Hannah Reyes/Getty Women from the Bunong indigenous group walk home in Mondulkiri, Cambodia.

The Cambodian human rights group LICADHO estimates more than 200 state-linked land deals have harmed 500,000 people, and the UN has called land-rights-related conflicts Cambodia's top human-rights problem.

Josie Cohen, land campaigner at Global Witness, which investigates economic networks behind environmental destruction, said land leases are "altering the very fabric of rural societies" in Cambodia and nearby Laos and Myanmar.

The Bunong of Bousra commune now must earn money to buy rice they once grew, and outsiders hold most of the plantation jobs. Despite promised development, many roads are still dirt.

Hannah Reyes/Getty Women from the Bunong indigenous group carry out their chores by their home. Cambodia's indigenous groups are at risk as their ancestral lands are being threatened by businesses interested in commercially developing the areas.

Kop Let, wife of a village chief, says her family has struggled since the plantation swallowed most of their 12 hectares (30 acres). She grows cassava on their remaining land, sells homemade rice wine and has taken out a $3,000 loan.

"I have now become a poor woman," she says. "Our identity as a people is disappearing little by little."

The Bunong say they never were warned their land would be taken and were not offered compensation before the land started to be cleared - two steps required under Cambodian law. Many say they felt forced to accept what they considered to be inadequate compensation.

Socfin, the Luxembourg-based agro-industrial company whose unit owns most of all three Bousra plantations, said it was invited by the government and that villagers were informed and compensated beforehand, but declined to provide evidence. Its joint venture with Cambodian developer Khaou Chuly Development Co., or KCD, operates two of the plantations.

"We brought wealth to a place where there was nothing," Socfin CEO Luc Boedt told The Associated Press in an interview in Brussels.

A 2009 legal analysis obtained by the AP and written by Maia Diokno, a human-rights lawyer hired by Socfin-KCD as a consultant, said the plantation work began without warning, and produced the "unfortunate result of dispossessing indigenous persons of their land."

"They didn't comply with Cambodian law," Diokno told the AP.

Even so, Sok Sam Ouen, a human-rights lawyer in Phnom Penh, noted that Cambodian authorities approved the lease-holder's actions.

Cambodia's environment minister, Say Sam Al, said the overall aim of the concessions program was to improve people's livelihoods throughout the country, but acknowledged problems in carrying it out. "We are changing that now," he said.

The government put a moratorium on new leases in 2012 and has reviewed each one. It revoked 40, but many disputes remain.

Today, Bousra's hills are covered in rows of rubber trees, many nearly ready to be tapped.

Most villagers are trying to negotiate with Socfin and key shareholder Bollore Group to seek better roads, services and jobs. They've joined forces with communities in four African countries - Cameroon, Liberia, Ivory Coast and Sierra Leone - that also have complaints about Socfin operations.

A smaller group of 83 villagers trying to get their land returned has filed suit against Bollore, which holds 39 percent of Socfin. Bollore declined to comment on the dispute.

Cambodia began granting land concessions in the late 1990s. No published official data measures their economic impact, but University of Copenhagen researchers estimate incomes of families living near concessions were 15 to 19 percent lower than they would have been had the leases never been granted.

The Bunong lost rice fields and grazing land, and were cut off from forest resources that once earned some families more than $2,000 a year, said Esther Leemann, a Swiss social anthropologist who has worked in Mondulkiri.

"There has been an impoverishment of the majority of the families," Leemann said.

Concessions require the approval of Cambodia's Council of Ministers, which operates with little oversight. The government has not revealed the leases' full extent; LICADHO said it has identified 272 covering 21,000 square kilometres , over a tenth of the country.

Violence and evictions have accompanied concessions. In 2012, security forces fatally shot a 15-year-old girl during a clash with residents. One case still before the courts stems from the 2006 eviction of some 4,000 villagers by armed military police to make way for a sugar concession.

"It has failed as a tool of development. It's a scheme for quick bucks," said Ou Virak, an economist in Phnom Penh.

Last month, Prime Minister Hun Sen declared the review process complete and pledged to return nearly 10,000 square kilometres to poor families. But human-rights groups doubt the figures and that land would actually be returned.

Socfin says it invested $80 million to create the plantations, pay workers and construct roads, a school and employee housing. The company says families cultivating rubber could earn more than $10,000 a year.

"I invite you to spend only one night in Bousra village, and you will know how poor it is," Boedt said. "And this gives the occasion for the people to get out of that misery."

Yet villager Yin Rouey considers the day the bulldozers rumbled in to be the most devastating moment of his life - worse than losing half his family to US bombs in the Vietnam War.

"In war, people die, but that's not as bad as losing our land," he said. "For us, if there's no land, it will kill us."

Some villagers worry the bulldozers destroyed something forever: their ancestral religion.

"They are afraid the spirits are angry at them because we haven't taken care of them," said Neth Prak, an informal community representative. "They killed the trees, and the spirits were there.

"Should I still pray to this forest?" he asked. "Where are the spirits now?"