Golden langur (Trachypithecus geei) was first sighted in Kokrajhar district in the year 1953 near Jam Duar of Raimona Forest Range ( Ripu Reserve Forest) by Mr. E.P. Gee, a naturalist. The word 'langur' is derived from the Sanskrit word 'langulin' meaning long tail.

The natural habitat of the Golden langur is between the river Sankosh and Manas along the marginal part of the foothills of eastern Himalayas. The extended habitat of this animal is the Chakrasila Wildlife Sanctuary near Kokrajhar.

The Golden langur is now endemic to the above habitat and is a critically endangered species. It is also included in the Schedule-I of the Wildlife Protection Act.