The northern plains grey langur (Semnopithecus entellus), also known as the sacred langur, Bengal sacred langur and Hanuman langur, covers a large portion of India from the Himalayas south to the Tapti River and the Krishna River. It lives in groups of varying composition. The most common type is the harem structure of one adult male together with several adult females and their offspring.
Langurs, unlike monkeys, have long tails and are also bigger – in fact, the word "langur" means 'having a long tail'. Langurs are considered more agile than monkeys. Bengal Hanuman langurs take their name from the Hindu god Hanuman. According to his story, his face, hands and feet were burnt black when he tried to save his wife from a fire. His black body parts are just like those of the Bengal Hanuman langurs.