Pastor Jesse’s mud-plastered Mitsubishi SUV jolted wildly along the newly dug dirt road that zigzagged up the mountainside toward the construction site of the new church. We stopped to let a pedestrian squeeze by, a middle-aged Lisu woman with a pink, checkered headscarf and a giant bamboo back basket which was strapped to her forehead. The Lisu are one of the 55 ethnic minorities of China and the predominant tribespeople in Gongshan, which nestles on the slope of the Gaoligongshan mountain range. Only 30 miles to the north, these mountain peaks reach more than 16,000 feet. Beyond that is Tibet.

It was a sun-drenched Saturday morning in December 2014. I had arrived the night before on my first visit to the area after reading Chinese media reports of the explosive growth of Christianity among the Lisu people in the “Gospel Valley,” as the Upper Salween River Valley is known. The church under construction is called Zion. It replaces a smaller one built in 1998 with members’ shovels, picks, baskets, and bare hands.

“Brothers and sisters brought their own bedrolls and woks and camped over there during construction of the first church,” Pastor Jesse said, gesturing toward the terraced fields up the slope. “Almost all the construction material was carried up here in bamboo baskets.”

That included stone quarried from the mountainside nearby. The church had no money, so the people did everything themselves. A decade and a half later, the congregation had outgrown the space, so the original building was dismantled to make way for the new. This time the people have a cement mixer, a miniature crane mounted on the highest floor, and a host of buckets.

The steel-and-concrete frame was more than half complete. On the east side, overlooking the deep gorge of the Salween River, the building rises seven stories high, its bottom floor a reinforced version of the stilts that still support older wooden houses perched precariously on the mountainside. The new sanctuary will hold up to 700 worshipers; other rooms will house several dozen seasonal seminary students.

Since 2000, theological classes have been held at Zion for the training of mizipa (deacons), mapa (evangelists), and Sunday school teachers—men and women in their thirties and forties who come from other towns and villages. Many have to cross the mountains on foot to get here. The deacon training takes two years—one semester a year, from late spring to fall. After that the mountain passes disappear under heavy snows.

“There.” Pastor Jesse pointed toward a nondescript house a hundred yards away. “That’s where Mr. Morse had his straw hut and ran his Bible training classes.” Like other Lisu Christians, Jesse goes by a biblical first name.

He was referring to Russell Morse, the Church of Christ–turned–independent missionary whose work among the Lisu led to thousands of conversions in the 1930s and ’40s. Jesse’s grandfather A-ci had attended Morse’s Bible classes.

The sparsely populated Upper Salween Valley may seem an unlikely place for a Christian community to thrive. Canadian missionary Isobel Kuhn of the China Inland Mission likened its topography to a “monster dump heap of all the excess rock and debris” of China, through which “the Salween River has tried to escape, boiling and thrashing its way with impotent fury at the strength of the cool resisting granite.”

Across the river from Gongshan are the Biluo Snow Moun­tains, called “the mountains of icy waves” by 13th-century Mongol conquerors. To American airmen flying DC-3s and Curtiss C-46s from India to West China during World War II, they were known as the “Big Hump.” This was the most dangerous terrain for the fliers. “Ice can build up so rapidly on the wings that within five minutes a plane loses all flying capacity and drops like a rock into the jungle,” wrote wartime correspondent Theodore White.

I first met Jesse on Friday, when I arrived in the Upper Salween Valley. A mutual friend had put me in touch with him. He had a packed schedule over the weekend, with stops at various places, but was willing to take me along.

Jesse, who is in his midforties, is from a Lisu clan called Bees, a name that both denotes their traditional occupation as honey gatherers and hints at the focus of the clan’s former totem worship, as do other clan names such as Tigers, Bears, and even Buckwheat and Tea. His grandfather A-ci had hailed from a village nearby.

A hot-tempered man, A-ci had always defied the outside powers that periodically descended on his mountain hamlet—be they Tibetan bandits or Han Chinese officials sent by the Nationalist government. The Bible that Russell Morse taught spoke to his place and time: the hated Chinese officials were the equivalent of scribes and Pharisees. He would have nothing to do with them. When he was told to help carry their sedan chairs to the next village, he flatly refused. There is a fierce independence running in the Lisu blood.

During a communist witch hunt for “counterrevolutionaries” in the late 1950s, all Lisu pastors were arrested. Christians in A-ci’s village were “struggled against” at denunciation meetings. But nobody came after A-ci. “Everybody knew he was a big and impetuous man,” Jesse said.

“He announced that if they dared to come to drag him out to the struggle meetings, he would cut down a few with his long sword and run over to Burma that very night,” Jesse added with a laugh.

A-ci not only fended off the attack on his faith; he also managed to hide Lisu Bibles, tracts, and hymnals in a cave. Those treasures were dug out after 1979, when the Communist Party relaxed its religious policies.

The Bibles and hymnals printed in the Lisu language held an uncommon place in the hearts of the tribespeople. Like most minority peoples of Yunnan province, the Lisu did not have a written language. They recalled a time when the Mother-God gave words to their forefather, who found a piece of deerskin and wrote them down. Then he laid the deerskin out in the sun to dry. But a wild dog came and ate up the piece of deerskin. And that was why the Lisu had no books.

The storied loss of written language weighed heavily on the Lisu, leaving them with an acute sense of deprivation. Yet the Lisu legends foretold the coming of a fair-skinned Lisu king who would bring books in the Lisu language.

In 1908, James O. Fraser of the China Inland Mission arrived to pioneer evangelistic work in western Yunnan. With the help of a Burmese Karen evangelist, Fraser developed a simple script based on the English alphabet to represent Lisu sounds. It became known as the Fraser script and was used to translate the Bible, starting with Mark’s Gospel.

For the Lisu tribespeople from the mountains, Fraser was the fair-skinned Lisu king who brought the books. Years later Kuhn lamented that Fraser’s “white-man appearance so monopolized interest that no one remembers his message.”

Fraser went on to oversee all the work of the CIM in Yunnan. He developed a strategy of training Lisu mapa and mizipa to carry the gospel into villages and to start new, self-supporting congregations. CIM missionaries also collaborated with the Lisu in Bible translation. In 1938, the year Fraser died, the first complete Lisu New Testament was printed in Shanghai.

The arrival of the Lisu Bible helped revitalize a languishing and battered Lisu ethnic identity. Without a common written language and condemned for centuries to a life of migratory slash-and-burn agriculture, the scattered Lisu tribes in Western Yunnan had developed local dialects that were at times mutually incomprehensible. Assimilation in lifestyle and language seemed inevitable as new waves of Han Chinese migrated into western Yunnan. Han domination and rapacious tax collection by headmen from other dominant ethnic groups further demoralized the Lisu tribespeople. Then came the Fraser script and the Lisu Bible, which breathed new life and cohesiveness into this migratory community.

At noon, Jessie and I left the construction site of the future Zion Church to deliver 1,000 Lisu hats to a church in a nearby village. The freshly completed church, painted a bright sunflower color, would be dedicated in two weeks and the hats would be souvenirs.

We were on the road again after the delivery. Jesse’s final destination that day was a mountain church in the village of Latudi in Fugong County 70 miles down the Salween River. We drove past a maroon church overlooking the river. Hundreds of triangle banners of red, pink, blue, green, and yellow fluttered in the wind on polyester strings that radiated from the rooftop to the ground on all sides.

“That church opened two weeks ago,” Jesse said.

Half an hour later we saw another small, new church on the roadside. “This one was built six months back.”

Invariably these churches are among the largest and brightest-colored buildings in a hamlet. Above them, the forested mountains rise at breathtaking angles, at times almost perpendicular, to form deep ravines. It was into these ravines that many of the hundreds of ill-fated American planes on the Hump flight plunged between 1942 and 1945.

In 1943, Russell Morse’s sons, Eugene and Robert, orga­nized a network of search and rescue teams made up of Lisu Christian tribesmen to locate and help downed airmen or to identify the bodies and give them a Christian burial. On March 29, 1944, four airmen were rescued. The Americans had landed in trees and their parachute lines were entangled in the branches. The Lisu team that found them cut the lines and escorted the airmen to the Morses’ home.

“That was a famine year,” wrote Gertrude Morse, Russell’s wife, “but our [Lisu] Christian brethren were very generous in sharing their meager supply of food with us and the fliers.”

In return for the rescue, the U.S. Army Air Force arranged for an airdrop: a military transport plane dropped 43 parachute packs of Lisu Bible primers and other supplies on a mountainside in Gongshan, where Gertrude Morse had made a big white cross with her bedsheets. For months, Lisu Christians glowed in amazement as they told of the “flying house” that had dropped God’s word from the sky.

There were no roads those days in the Upper Salween Valley—only mountain footpaths over a dizzying drop down the bank. Today, the asphalt two-lane highway is clogged with the cars of Han Chinese tourists, local tractors carrying cement and steel bars, and trucks hauling hardwood timber harvested in Myanmar. The outside world has broken into this canyon.

In one village, a barefooted man wearing a greasy olive-green army uniform with no epaulets staggered down the center of the road, his ankles and feet the color of the mountain’s red dirt. He clutched a bottle of liquor in his left hand and raised his right hand to give our vehicle a sloppy salute. Alcoholism was rampant among the Lisu when the missionaries first arrived, and it still plagues a sizable portion of the non-Christian population. It is estimated that in the early 20th century, more than 12 percent of the area’s harvested grain was used for liquor. Many villages had to endure food shortages for four months out of each year.

As Christianity spread in the valley, a modified Lisu Ten Commandments banned drinking, gambling, and opium smoking along with brawling and traditional dancing and singing. “Satan and sin have given them a set of licentious yodel songs,” protested Kuhn. “On the surface it is nature talk, as of birds, or the meetings of streams, but each is a metaphor so vile that no Christian Lisu will translate it for you.” Today the yodeling is gone, much to the exasperation of anthropologists.

It was dark when we finally arrived at Latudi. In the stillness of the night, the choir was practicing for the worship the next day. Peals of laughter punctuated the sound of women singing bubbly Lisu hymns. Seven or eight middle-aged and older men, deacons and elders of the church, welcomed us to a hearty supper of rice, home-raised silkie chicken, and mustard greens. After dinner they beckoned us to sit around the fire—a heavy metal basin loaded with chunks of charcoal. The tanned faces of the men glowed in the firelight as they told stories and traded jokes. I could not see in those faces any trace of the horrendous suffering borne by the entire Lisu tribe half a century ago—a wave of violent persecution that swept through the valley. Latudi was near its epicenter.

First came sporadic instances of threats and violence. “One of our beloved Lisu preachers was punished by having his ears, nose, and tongue cut off,” reported Gertrude Morse, whose family moved into Burma after 1949 to continue their work among the Lisu there.

Then came the counterrevolutionary case of 1958. In May, Cha Shumin, a Lisu, led a guerrilla force of some 400 in an incursion into the Upper Salween Valley from Burma. They killed a dozen local Communist Party officials and activists. As the intruders fled back into Burma, Cha left behind a briefcase containing a pair of binoculars and a blueprint for a “Lisu Kingdom,” which included a list of proposed top court officials. Most were prominent Lisu Christians who had been chosen to serve in local government posts because of the superior education they had received in church-run schools.

What followed the attack was a massive police operation in the Nujiang (the Chinese name for Salween) Lisu Autonomous Prefecture to hunt down “counterrevolutionaries” who were plotting to establish the fictitious Lisu Kingdom. The prefectural party secretary set a quota of several thousand counterrevolutionaries for every county. More than 10,000 Lisu were arrested on suspicion of harboring pro-American sentiments. Most of them were Christian, and 5,000 of them were killed or perished in labor camps.

Jails in the Upper Salween Valley quickly filled up, and the overflow was directed to neighboring counties. Those arrested in Fugong were marched over the icy Biluo Snow Mountains to be imprisoned in Lanping County. Even women still nursing their babies were dragged away, barefooted. One public security officer later recalled: “A group of Lisu were under escort . . . They either had their hands bound or handcuffed and some were even in fetters. . . . The straggling line stretched out several kilometers,” and the valley reverberated with “the intermittent clanking of the chains.”

These events prompted an estimated 30,000 to flee to Burma. In all, some 40,000 Lisu migrated to northern Burma between 1949 and 1966 (the year when the Cultural Revolution broke out), including 10,000 Christians. Churches were razed or closed, and the remaining Christians were driven underground.

“In one village, some Lisu Christians recovered a wooden post that had supported the church before it was torn down,” said Bobby Morse, the grandson of Russell Morse and a missionary in Chiang Mai, Thailand. “And they carved the Lisu New Testament on the post.”

The rebirth of the Lisu church in the Upper Salween began in the early 1980s with the reappearance of the Lisu Bibles. The earlier generation of Lisu pastors was gone, so laypeople like A-ci began leading worship meetings in their homes. In 1983, Jesse became a Christian.

“Four years later, I dedicated myself to God,” Jesse said.

He soon started baptizing people in the bone-chilling water of the Salween River near Gongshan. They came in droves. And the baptisms have not stopped.

Development in Fugong is even faster-paced. It has become the most Christian region in all of China, with church members accounting for about 70 percent of Fugong’s roughly 90,000 residents. Their exceptionally low crime rate also makes the county an oasis in this heroin-infested province bordering the infamous Golden Triangle, a major opium-producing area. A few months earlier, in the picturesque town of Old Dali, I had followed an arrow pointing toward a Muslim restaurant and found, scrawled on a plastered white wall, the words “guns, sedatives, wireless tapping” next to a cell phone number. In the Gospel Valley, such thrills give way to the more mundane rhythm of corn harvests and Sunday worship. Each of the 360 or so villages in Fugong now has at least one church.

On Sunday Jessie led a thanksgiving worship to celebrate the addition of a reception hall to the church in Latudi. Worship drew about 400 people. They came in single file down the narrow dirt path, past terraced fields covered with canola flowers in bloom, past stone and concrete tombs at the end of the fields—Christian tombs, each with a faded red cross that had been painted on the front.

A 15-member female choir sang and swayed to the accompaniment of an electric guitar and drums played by two spirited boys. The women wore their Lisu Sunday best: black and wine-colored velvet vests with gold borders, over white shirts and pleated lavender skirts. The congregation spilled out into the courtyard; the people responded to Jesse’s sermon by singing hymns from the Lisu hymnal.

Later in the service, groups of ruddy-faced girls ascended the dais behind the lectern, dancing and singing gospel songs to the snickers of teenage boys and young men in the congregation—the closest they now get to yodeling.

On our way down the dirt mountain road after the worship, we stopped to give a ride to three girls, age ten to 12, who were on their way to the public boarding school at the foot of the mountain.

“Are your textbooks in Lisu?” I asked.

“No, they are in Chinese,” the ten-year-old told me. And so are the cartoons they watch on television and the pop songs that blast from storefront boom boxes to attract customers.

Across the river from the school, Fugong is cluttered with shops and gray office, hotel, and apartment buildings. Some euphemistically named “Thai-style massage” salons run by Han Chinese have opened up as shopkeepers, tourists, and traders in Burmese lumber and jade descend into the valley from coastal and inland China.

I wondered what will happen to the Lisu people. Will they stay in the Salween Valley or join the 250 million rural residents whom the government will move into China’s cities and towns over the next dozen years? Will their children lose their Lisu language when they grow up? If the history of the last several hundred years offers any clue, the Lisu people will be able to keep their way of life and an identity that is rooted in the Lisu language and now the Lisu Bible as well. Although the government introduced a “scientific” romanization system in the 1950s, today government publications have reverted back to the Fraser script. The Lisu Bible has endured.

And as the churches read from the Lisu Bible, they continue to attract new members and build new worship spaces. When Jesse dropped me off at a bus stop that afternoon, he offered me his blessings. He was heading back to Gongshan for an evening prayer meeting at Zion.

This version of the article contains a correction from the print edition, regarding the number of ethnic minorities in China.