Nepal, May 31 -- Just two decades ago, the village of Dhuli in the hills of west Nepal resounded with a language unlike any other. Spoken primarily by the Rokaya, Kami and Bohara communities, Dhuleli was once the lingua franca of thousands of people across half a dozen villages in west Nepal. Today, it is on the brink of vanishing.

"Two decades ago, most of us didn't understand Nepali. Dhuleli was our preferred language," says Matbir Rokaya, whose native language is Dhuleli. "But since our children have started moving out of the district, they've taken to speaking other languages, and now most young people have forgotten to speak their own language."

According to UNESCO, there are five categories for endangered languages-vulnerable (mos...