The lutungs, langurs, or leaf monkeys are a group of Old World monkeys in the genus Trachypithecus (derived from Greek τραχύς, trachýs meaning "rough" and πίθηκος, píthekos meaning "monkey"). Their range is much of Southeast Asia (northeast India, southern China, Borneo, Thailand, Java, and Bali).
The name "lutung" comes from the Sundanese language and means "blackness"; it is preferred in one paper because the authors wanted the name langurs to only refer to monkeys in the genus Semnopithecus, although some "lutungs" are now "langurs" again.
Lutungs live in the forests, often preferring rain forests, although occasionally they are also found in secluded mountain forests. Lutungs are found in South-east Asia and parts of South Asia from India in the west to China in the east.