Gibbons are apes in the family Hylobatidae. The family historically contained one genus, but now is split into four genera. Gibbons occur in tropical and subtropical rainforests from eastern Bangladesh and northeast India to southern China and Indonesia (including the islands of Sumatra, Borneo, and Java). There are nine species found in South east Asia of entirely arboreal apes. They are the smallest, lightest and most agile of the apes. Orangutan is largest living arboreal mammal living in rainforests of Sumatra and Borneo. Gorilla is the largest of all primate species, where male weigh about over 200 kg. Chimpanzee are very close to man and are Knuckle walkers.