SANJIAZI, China — Seated cross-legged in her farmhouse on the kang, a brick sleeping platform warmed by a fire below, Meng Shujing lifted her chin and sang a lullaby in Manchu, softly but clearly.

After several verses, Meng, a 82-year-old widow, stopped, her eyes shining.

"Baby, please fall asleep quickly," she said, translating a few lines of the song into Chinese. "Once you fall asleep, Mama can go to work. I need to set the fire, cook and feed the pigs."

"If you sing like this, a baby gets sleepy right away," she said.

She also knows that most experts believe the day is approaching when no child will doze off to the sound of the song's comforting words.

Meng is one of 18 residents of this isolated village in northeastern China, all over 80 years old, who, according to Chinese linguists and historians, are the last native speakers of Manchu.

Descendants of semi-nomadic tribesmen who conquered China in the 17th century, they are the last living link to a language that for more than 2 1/2 centuries was the official voice of the Qing dynasty, the final imperial house to rule from Beijing and one of the richest and most powerful empires the world has known.

With the passing of these villagers, Manchu will also die, experts say. All that will be left will be millions of documents and files — about 60 tons of Manchu-language documents are in the provincial archive in Harbin alone — along with inscriptions on monuments and important buildings in China, unintelligible to all but a handful of specialists.

The disappearance of Manchu will be part of a mass extinction of languages that some experts forecast will lead to the loss of half of the world's 6,800 languages by the end of the century. But few have declined so rapidly, from such prominence, as Manchu.

Within decades of establishing their dynasty in 1644, the Qing rulers brought all of what was then Chinese territory under control and then embarked on a campaign of expansion that roughly doubled the size of their empire to include Xinjiang, Tibet, Mongolia and Taiwan.

However, the dynasty's fall in 1912 meant that the Manchus were relegated to the ranks of the more than 50 other ethnic minorities in China, their numbers dwarfed by the dominant Han, who today account for 93 percent of the country's 1.3 billion people.

Indistinguishable by appearance, the Manchus have since melded into the general population. About 10 million Chinese citizens now describe themselves as ethnic Manchus.

For generations, the vast majority have spoken Chinese as their first language. Manchu survived only in small, isolated pockets like Sanjiazi.

Traditional shamanistic rites with ethnic dress and customs have been mostly abandoned, although some wedding and funeral ceremonies retain elements of Manchu rituals, Zhao said. But villagers still observe one Manchu taboo that sets them apart from others in China's far northeast.

"We don't eat dog meat," Zhao said. "And we would never wear a hat made from dog fur." The prohibition, tradition has it, honors a dog credited with having saved the life of Nurhachi (1559-1626), the founder of the Manchu state.

Use of Chinese has spread sharply in recent decades as roads and modern communications have exposed the villagers to the outside world. Only those of Meng's generation prefer to speak Manchu. "We are still speaking it, we are still using it," said Meng. "If the other person can't speak Manchu, then I'll speak Chinese."

While most experts agree that Manchu is doomed, Xibo, a closely-related language, is likely to survive a little longer. Xibo is spoken by about 30,000 descendants of members of an ethnic group allied to the Manchus who in the 1700s were sent to the newly conquered western region of Xinjiang.