Is it farther or further?
1776, from Hindi jangal "desert, forest, wasteland, uncultivated ground," from Sanskrit jangala-s "arid, sparsely grown with trees," of unknown origin. Specific sense of "land overgrown by vegetation in a wild, tangled mass" is first recorded 1849; meaning "place notoriously lawless and violent" is first recorded 1906, from Upton Sinclair's novel (cf. asphalt jungle, 1949, William R. Burnett's novel title, made into a film 1950 by John Huston; blackboard jungle, 1954, Evan Hunter's novel title, movie in 1955). Jungle gym was a trademark name, 1923, by Junglegym Inc., Chicago, U.S. Jungle bunny, derogatory for "black person," attested from 1966.