Harvey (c1992) says that this language has probably been extinct since WW2, and to his knowledge there are no sources on this language.
West of the South Alligator River between Ga'baarlgu and Mt Hooper (Top End Handbook). The general associations were to the coast west from the mouth of the South Alligator to and including Carmor Plain. Thrings Creek was associated with Limilngan. Barron Island appears to have been associated with Gonbudj. Field Island was associated with Ngaduk. There was no precise information on the inland limits of Gonbudj in 2007. The most reliable information on Gonbudj is the information provided by Fred Wardiirdi to Berndt & Berndt in 1949. As recorded in Berndt & Berndt (1989), Fred associated Carmor Plain (pp25-26), Marrabibi Hill (p34). Other statements about Gonbudj are recorded at p62-63, p104 (Harvey ASEDA 802).
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).