Natural rubber, also called India rubber or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Thailand and Indonesia are two of the leading rubber producers.
Thank you very much"India-rubber" was common up to perhaps the mid-twentieth century in Britain, for what we now call "rubber" (noun, both "a rubber" (eraser) and the material). OED has an example from How to be Topp by Geoffrey Willans (1954), which shows it must have been common use in schools (sorry, skools ) at the time, although I am pretty sure it must have quickly died out after then. OED has no later entries that don't have at least some element of referring back to an earlier age, and maybe using obsolete language to match.