Zingiber officinale is not known to exist in a wild state anywhere; every cultivated plant has been propagated vegetatively from rhizome cuttings, generation after generation, for long enough that no confirmed wild population has ever been identified. Competing accounts place the likely point of origin in India or in Maritime Southeast Asia among Austronesian-speaking peoples, without resolving the question.
What would resolve this Discovery and genetic confirmation of a true wild Zingiber officinale population, or comparative genomic work establishing which existing wild Zingiber species is its closest relative and where that species is native, either of which would narrow the search for where and when domestication took place.
OpenBotany and plant genomics, specifically phylogenetic comparison across wild Zingiber species.Alan Davidson, The Oxford Companion to Food