Opening the church door in Baihanluo reveals a large portrait of Pope Francis -- something of a paradox in an ethnically Tibetan area of Communist China.

The village is only reachable on foot or by horse, and surrounded by snow-capped Himalayan peaks.

But despite its remoteness French missionaries built the church -- with a curved, Chinese-style roof -- at the end of the 19th century.

Pope Gregory XVI assigned Tibet to the Foreign Missions Society of Paris, shortly after China was forced to open its doors following its defeat in the First Opium War.

Heading up the river valleys into the hills, cut off by snows in winter, they established "lost missions" in a still largely traditional and theocratic society.

At times it was a bloody cause, with evangelists martyred by monks opposed to Christ invading their Buddhist territory.

"It was China's far west. In Chinese, the Nu river was nicknamed the Valley of Death. The saying was you had to sell your wife before going because you didn't know whether you'd come back," said Constantin de Slizewicz, author of The Forgotten Peoples of Tibet.

After the Communist victory in China's civil war in 1949, foreign missionaries were arrested as "agents of imperialism", maltreated and expelled.

- Decades without priests -

"The churches were closed, or converted into schools or barns. Christians could be jailed for having religious objects, and those who had important roles were persecuted or taken for re-education," de Slizewicz told AFP.

But Catholicism persisted among the rural peasantry, their fervour as enduring as their poverty.

"Tibetans are mad about God. They dedicate their lives to their faith. Tibetan Catholics don't convert by half," said de Slizewicz.

"In nearly 50 years without priests or sacraments they did not lose a single word of a century of the fathers' teachings."

The mayhem of Mao's 1966-76 Cultural Revolution brought with it another round of destruction.

But as well as maintaining the missionaries' tombs, the Tibetans have continued to recite the catechism -- some in Latin -- and celebrate Easter and Christmas, replacing the donkey and ox of the stable with a mule and a yak.

Now, in a less intolerant climate, as many as 500 parishioners gather for festivals in Baihanluo, perched on a mountain spur in the southwestern province of Yunnan, and recall the Nu patriarch Zachary, who died around a decade ago aged more than 100.

He escaped the Communist purges by fleeing to Taiwan, but returned after 30 years of exile to join in the local Catholic revival.

"Zachary put holy water from Lourdes, diluted in spring water, in every church in the neighbourhood," said Zha Xi, 32, baptised Joseph. "One drop was given to a sick believer, and three days later he was virtually cured."

A Baihanluo native called to the priesthood, Joseph has studied at seminaries in Kunming and Chengdu, and is now preparing for the ministry.

There are 16 churches in the area and farmer Yu Xiulian, 75, said: "There are more and more Catholics here. We ordinary people want to make the churches bigger but there isn't the money."

- Dalai Lama -

Parish priest Han Sheng, 39 -- known as Father Francis -- says there are more than 10,000 Catholics in Tibetan areas of China, half of them in Gongshan district, which includes Baihanluo.

China's Communist authorities require religion to be supervised by the state -- in the case of Catholics, by the Chinese Patriotic Catholic Association, which oversees the churches of Gongshan.

A separate "underground" Chinese church recognises the authority of the Pope.

The vast majority of religious Tibetans are Buddhists, more than 130 of whom have set themselves on fire since 2009 in protest at Chinese rule, most of them dying.

Beijing accuses the exiled spiritual leader the Dalai Lama of separatism and has called him "a wolf in monk's robes", accusing the Nobel laureate last month of backing "ethnic cleansing".

He was denied a meeting with the Pope when he visited Rome in December, apparently as the Vatican sought to avoid upsetting Beijing.

Father Francis echoes the official line on the issue. "Speaking of the Dalai Lama, we regard him highly as a religious leader," he told AFP. "But we don't want him to carry out separatist activities."

He attributes the growing number of faithful to the missionaries' historical legacy, rather than a contest of beliefs between Buddhism, Catholicism and Communism.

At night, an icy draught blew through one of the district churches as women and children sat on one side of the aisle, men on the other.

Simply dressed, their skin tanned by altitude and field work, they knelt one by one to whisper confessions of their sins to a priest by the altar.

"If we follow Your Words, we will go to Heaven," the congregation chanted tirelessly.