While documenting two little known languages, Aka and Miji, researchers traveling through the foothills of the Himalayas discovered a "hidden" language - Koro. The newly recognized language is spoken by about 800 to 1,200 people in Arunachal Pradesh, a remote region of northeast India, and belongs to the Tibeto-Burman language family, which is composed of a group of about 400 languages. It is thought that around half of the world's nearly 7,000 known languages are endangered, and experts believe that Koro is among those vulnerable to extinction.