Bangladesh’s Sundarbans mangroves in the Gulf of Bengal are witnessing an expansive paradigm shift to Bengal tiger-focused conservation and commercial aquaculture that severely affect customary livelihood rights, local harvesting regulations, and indigenous cultural survival of local groups. This study presents an in-depth empirical case of an Indigenous Munda community’s local experiences and responses to the regional land use governance transformation, using ethnographic field data within a political ecology approach. The analysis focuses on two aspects: First, shifting dynamics of adapted livelihood practices and conservation ethos, embedded in empirical accounts and relational ontology of traditional Munda human-environment conceptualizations that guide tiger-human interactions and emphasize the wellbeing of land, forest, and wildlife centered in the myth of the forest goddess Bonbibi, the spiritual guardian of the Sundarban. Second, the case study traces land grabbing effects of the recent regulatory shifts, dispossession and systemic marginalization impact on the loss of Munda livelihood foundations and culture, rendering the Indigenous Munda as “forgotten people” in the Sundarbans. The critical lessons of this case highlight the significance of a more holistic alternative to dominant single-species tiger conservation governance interventions, identifying a missed opportunity in regional value-based conservation politics to re-embed and strengthen the traditional knowledge contributions, cultural practices, and worldviews of Indigenous Munda. Finally, the analysis urges that the spiritually based livelihood practices, rules and ecocentric respect of Indigenous Munda require formal recognition of land rights for their cultural survival.