This paper examines the crisis of indigenous knowledge systems among Scheduled Tribes in two ecologically distinct regions of India, which are the forested heartland of Madhya Pradesh and the deltaic Sundarbans of West Bengal. Drawing on ethnographic fieldwork, Participatory Rural Appraisal (PRA), and interview-based data collected, the study argues that tribal knowledge systems encompassing medicinal traditions, seed biodiversity, oral literature, artistic practices, and indigenous languages are undergoing profound erosion in both regions, though at different rates and through different mechanisms. In Madhya Pradesh, the process is largely characterised by gradual acculturation driven by formal schooling, market forces, and migration, while leaving core knowledge structures partially intact. The region is known for Gondi art of the Gond tribe but most of the art-forms of other tribes do not exist in popular imagination. In the Sundarbans, epistemic marginalisation has advanced further, compounded by ecological instability, language shift toward Bengali, and institutional neglect. These dynamics are analysed within the framework of ‘epistemic marginalisation’, drawing on the work of Escobar (1995) and Xaxa and Devy (2021) to argue that the erosion of knowledge systems is inseparable from the erosion of identity. The emergence of a pluriversal approach to development seems more viable and effective since it recognises indigenous epistemologies as dynamic, and indispensable to sustainable futures through evidence-based applications.