Hima is one of the last remaining Kusunda, a tiny indigenous group now scattered across central western Nepal. Their language, also called Kusunda, is unique: it is believed by linguists to be unrelated to any other language in the world. Scholars still aren't sure how it originated. And it has a variety of unusual elements, including lacking any standard way of negating a sentence, words for "yes" or "no", any words for direction, or even a set grammatical structure.

According to the latest Nepali census data from 2011, there are 273 Kusunda remaining. But only one woman, 48-year-old Kamala Khatri, is known to be fluent.

https://www.bbc.com/future/article/20220804-kusunda-the-language-isolate-with-no-word-for-no