http://www.bbc.co.uk/news/magazine-23053593
California is home to the greatest diversity of Native American tribes in the US, and even today, 90 identifiable languages are still spoken there.
Many are dying out as the last fluent speakers pass away and English dominates. But one tribe is having success reviving the Yurok language, which was on the verge of extinction and now is being taught in schools.
Members of the tribe spoke to the BBC's Alastair Leithead about their efforts to save the language.