But there are six sub-species, or groups that lived apart in the wild for so long that they changed slightly. The Francois sub-species is the most common. There are believed to be about 100 langurs of the Francois sub-species left in northern Vietnam and 2,000 in southern China. There are only a few hundred of each of the other five sub-species. Their range is from central Vietnam north beyond the Chinese border and over into Laos.
Francois langurs live in areas with steep, craggy hills that look like camel's humps.
During the day, they stay mostly in trees, where they eat leaves and seeds. They're great leapers and jumpers. At night, they like to sleep in limestone caves to keep warm. Francois langurs are used in Asia to make medicine. And Vietnam's human population has exploded in the last 20 years.