As workers lift wooden boards from the roof of the cottage, an old man sits inside by the fireplace, calmly chanting from ancient scriptures, oblivious to the falling pieces of wood. Outside, an old woman watches them with deep grief in her eyes, for the room being taken apart was once her bedroom.

For the Mosuo people in Southwest China's Yunnan and Sichuan provinces, the flames in the family fireplace kept burning around the year in the granny's bedroom (or yimi in the Mosuo language), are believed to bring everlasting prosperity.

At the end of the demolition, the old woman steps up and puts out the fire with water.

"The deity who has been blessing our family will leave," she says, almost choking with tears. "I'm terribly sorry to my parents and ancestors. Money doesn't make sense to me."

The documentary, The Granny House Away from Home, captures the anguish the old woman experienced two years ago in Lijiazui village, Sichuan province.

The documentary is made by Erqing, also a Mosuo, and participant in the village video project sponsored by the EU-China Biodiversity Program. The project aims to show the nation's cultural and biological diversity through the eyes of the locals.

The Mosuo people are known for their matriarchal system, under which the utmost respect is attached to the senior-most woman in the family. It is her bedroom that serves as the family's center of everyday life.

The priest, or Daba, - a role that often falls on the oldest man in the family - makes offerings to the ancestors before every meal over the fireplace, called guozhuang, which is set in front of the altar. The fireplace is where all rituals - from celebrating births to quarantining the diseased - are performed.

In 2007, Dutch artist Mathilde ter Heijne and Tang Qifeng, co-organizer of Heijne's exhibition of Mosuo culture in Beijing, came to the village looking for a genuine yimi and offered 100,000 yuan ($14,600) for it.

Erche Pinchu, 35, and the oldest son of the family, saw it as a wonderful opportunity to turn around the family's fortunes.

A six-hour drive from Lugu Lake, Lijiazui village sits in the mountains and has been slow to develop. Electricity reached it only 7 years ago, but even now is available only in the evening. Telephone connections were not available until 2008. Villagers still make a living raising sheep and growing corn.

Pinchu's father died years ago and the family of seven survived on selling matsutake, or pine mushroom, and some medicinal herbs in the summer. Pinchu remembers that the most he made after toiling in the mountains for half a month, was 140 yuan ($20).

Ter Heijne, who did not answer requests for an interview, has created many works on the role of women. She came up with the idea of the exhibition after reading the book A Society without Fathers or Husbands: The Na of China by Chinese anthropologist Cai Hua, according to Erqing and Ter Heijne's website.

Even though Pinchu tried very hard to persuade his family and the villagers that selling the family's yimi was a worthwhile deal, no one backed him up, except for his girlfriend Wong Pakngan. The Hong Kong native toured Lijiazui in 2005 and fell in love with the handsome and honest young man.

Erqing captures well the wrenching emotions triggered by the controversial sale. The documentary has Pinchu expressing the overwhelming pressure he came under.

"My mother was quite heartbroken and her reproach nearly drove me nuts," he says. "But I really hope that if the exhibition and the ones to follow are held abroad as the artist says they will be, it can contribute to our village's development."

But his mother says: "I told the foreigner I will definitely not sell it, yet Pinchu insists on the deal. I'm just fed up with the endless quarrels."

On the day the cottage was taken apart, Pinchu gathered his whole family for one last photograph in front of the 200-year-old wooden structure occupying 26 sq m - the village's smallest. Not one Mosuo villager turned up to help with the dismantling.

Half a year later, Pinchu's mother moved into a new house, decorated with sacred symbols such as antelope antlers and streamers covered with religious texts. The new house cost the family 10,000 yuan more than what they earned from the sale of the old. Pinchu now lives in Hong Kong with his wife. Illiterate and unaccustomed to urban life, he spends most of his time indoors.

Already given the cold shoulder by fellow villagers, he says he has also been cheated by outsiders armed with knowledge and money.

In a phone interview, he reacts with indignation when told that a replica of his family's yimi, smaller and made of polyurethane, had been exhibited in Berlin and Amsterdam last year.

He recollects that Ter Heijne and Tang had promised that whenever his family house was put on display, he would be informed beforehand and invited to be there with his mother and wife.

Erqing's documentary ends with a shot of Pinchu's mother smiling at relatives and friends gathered for a banquet on their first day in the new house.

"But I know, though I never ask, that it's a painful memory," says Erqing.

The documentary will soon be shown on the documentary channel of Yunnan TV.