The language, called Koro, belongs to the same family of languages as Tibetan and Burmese, linguists Gregory Anderson of Swarthmore College in Pennsylvania, David Harrison of Oregon's Living Tongues Institute and Ganesh Murmu of India's Ranchi University, reported.
Anderson, Murmu and Harrison, backed by National Geographic, had to get special permission from the Indian government to visit the Arunachal Pradesh state bordering Bhutan and China, where they found Koro speakers.
Most are elderly, Anderson said. "We were finding something that was making its exit, was on its way out," Anderson said in a statement.
"And if we had waited 10 years to make the trip, we might not have come across close to the number of speakers we found."
Residents of the Himalayan region, who farm pigs, rice and barley, spoke two known languages called Aka and Miji but the linguists heard unfamiliar words that turned out to be Koro.
"We didn't have to get far on our word list to realize it was extremely different in every possible way," Harrison said in a statement.
While the Aka word for a pig is "vo," Koro speakers call it "lele," for instance. It also has a unique grammar.
"Koro could hardly sound more different from Aka," Harrison writes in "The Last Speakers," a book being published by National Geographic about the work. "They sound as different as, say, English and Japanese."
Harrison believes Koro may have origins in the slave trade.
Harrison has been reporting for years on dying languages and estimates a tongue becomes extinct every two weeks. Many languages are spoken only by a few elderly residents of a region and many, like Koro, have never been written down or recorded in any way.
"On a scientist's tally sheet, Koro adds just one entry to the list of 6,909 languages worldwide," Harrison said.
