QAPQAL XIBE AUTONOMOUS COUNTY, China >> Loyal to the core and prized for their horsemanship, several thousand Manchu soldiers heeded the emperor’s call and, with families and livestock in tow, embarked in 1764 on a trek that took them from northeastern China to the most distant fringes of the Qing dynasty empire, the Central Asian lands now known as Xinjiang.

It was an arduous, 18-month journey, but there was one consolation: After completing their mission of pacifying the western frontier, the troops would be allowed to take their families home.

“They were terribly homesick here and dreamed of one day going back east,” said Tong Hao, 56, a descendant of the settlers, from the Xibe branch of the Manchus, who arrived here emaciated and exhausted. “But sadly, it was not to be.”

But 2-1/2 centuries later, the roughly 30,000 people in this rural county who consider themselves Xibe have proved to be an ethnographic curiosity and a linguistic bonanza. As the last handful of Manchu speakers in northeast China have died, the Xibe have become the sole inheritors of what was once the official tongue of one of the world’s most powerful empires, a domain that stretched from India to Russia and formed the geographic foundation for modern China.

In the decades after the revolution in 1911 that drove the Qing from power after nearly 300 years, Mandarin Chinese vanquished the Manchu language, even in its former stronghold in the forested northeast. But the isolation of the Xibe in this parched, far-flung region near the Kazakh border helped keep the language alive, even if its existence was largely forgotten until the 1940s.

For scholars of Manchu, especially those eager to translate the mounds of Qing dynasty documents that fill archives across China, the discovery of so many living Manchu speakers has been a godsend.

“Imagine if you studied the classics and went to Rome, spoke Latin and found that people there understood you,” said Mark C. Elliott, a Manchu expert at Harvard University who said he remembered his first encounter, in 2009, with an older Xibe man on the streets of Qapqal county. “I asked the guy in Manchu where the old city wall was, and he didn’t blink. It was a wonderful encounter, one that I’ll never forget.”

Despite the local government’s best efforts, which include language instruction in primary schools and the financing of a biweekly newspaper, what is known here as Xibe is facing the common fate of many of the world’s languages: declining numbers of speakers and the prospect of extinction.

The publication Ethnologue identifies almost 300 living languages in China, half of them on the edge of the abyss as Mandarin, the nation’s official language, continues to subsume minority tongues. Among those under pressure, 20 have fewer than 1,000 speakers, according to the website The World of Chinese.

Although many young people here still speak Xibe at home, few of them can read its graphically bold script, made up of 121 letters and written vertically, from left to right. One recent day in the offices of The Qapqal News, a four-page gazette composed mostly of articles translated from the state-run news media, He Wenjun, 72, a teacher and translator, said he worried that his children and grandchildren could not read or write Xibe.

“Language is not only a tool for communication, but it ties us to who we are and makes us feel close to one another,” said He, who has spent decades translating imperial Qing documents into Chinese. “I wonder how much longer our mother tongue can survive.”

Even as intermarriage and migration to other parts of the country dilute their identity, the Xibe remain proud of their history and especially their role helping to secure the lands that greatly expanded China’s borders. It was a Manchu emperor who tapped the Xibe to settle the Ili Valley here after Qing soldiers massacred or exiled the nomads who had long menaced the empire’s western borderlands.

In the decades that followed, a succession of rebellions, many of them led by the region’s ethnic Uighurs, kept the Xibe garrisons busy and sometimes thinned their ranks. One battle in 1867 nearly halved the Xibe population, to 13,000.

Until the 1970s, the Xibe remained isolated from the ethnic Kazakhs and Uighurs who settled Ghulja, a city that sits on the far side of the Ili River. The Xibe also ate pork and practiced a blend of shamanism and Buddhism, making intermarriage with the Muslim Kazakhs and Uighurs relatively rare.

“We happily lived in our own world and rarely took boats to the other side of the river,” said Tong Zhixian, 61, a retired forestry official who sings and performs traditional Xibe dances at the county’s new history museum.

The Xibe language has gradually evolved from Manchu as it absorbed vocabulary from the Uighurs, Kazakhs, Mongolians and even the Russians who passed through Xinjiang. Unlike Mandarin, which has few borrowed words, Xibe is flecked with adopted nouns like pomodoro (tomato), mashina (sewing machine) and alma (the Uighur word for apple). Scholars say that the phonetic diversity of Xibe, a language thought to be related to Turkish, Mongolian and Korean, allows speakers to easily produce the sounds of other tongues.

“We fought with the other groups, but there were so few of us here and no one else spoke our language, so we had to learn theirs to survive,” said Tong, an engineer at the county power company who is vice president of the Xibe Westward March Culture Study Association, a local group that promotes Xibe language and history. “That’s why we are so good at learning foreign languages.”

Those linguistic talents have long been an asset to China’s leaders. In the 1940s, young Xibe were sent north to study Russian, and they later served as interpreters for the newly victorious Communists. In recent years, the government has brought Xibe speakers to Beijing to help decipher the sprawling Qing archives, many of them of imperial correspondence that few scholars could read.

“If you know Xibe, it takes no time for you to crack the Qing documents,” said Zhao Zhiqiang, 58, one of six students from Qapqal county sent to the capital in 1975, and who now heads the Manchu study department at the Beijing Academy of Social Sciences. “It’s like a golden key that opens the door to the Qing dynasty.”

But generous government funding might not be enough to save the language of the Manchus. At the county museum here, a sprawling collection of dioramas depicting the westward exodus, Tong spends most days performing to an empty room. After one recent performance, an ensemble piece that featured Xibe matrons twirling with very large knives, he wondered aloud whether he might be the last of his generation to keep such traditions alive.

“Young people just aren’t interested in this kind of thing,” he said, wiping the sweat from his brow. “Sure, they might study some Xibe in school, but once they leave the classroom, they plunge right back into Mandarin.”

© 2016 The New York Times Company