In the culturally diverse state of Jharkhand, India, the Birjia tribe is a Particularly Vulnerable Tribal Group (PVTG). This research explores the complex cognitive aspects of kinship within this PVTG. The foundation of the Birjia people's social structure is their unique patrilineal kinship system, which they have managed to preserve in spite of external pressures and modernization. This study reveals the cognitive foundations of Birjia kinship through an anthropological investigation, providing insight into how this indigenous group views, internalizes, and practices its familial relationships. Using anthropological ideas of kinship, particularly the concept of moiety, this study clarifies the dualistic structure inherent in Birjia kinship, which splits people into two complementary groups, each with distinct tasks and responsibilities. Furthermore, this study uses a cognitive anthropological perspective to investigate how Birjia people understand familial ties, tracking the thought processes associated with inheritance patterns, alliance building, and kinship classification. This study reveals how Birjia kinship affects people's sense of self, identity, and social belonging through a blend of cognitive analysis and ethnographic evidence. It demonstrates how cognitive schemas ingrained in the Birjia community's cultural fabric affect interpersonal interactions, communal dynamics, and decision-making processes. This study also highlights the Birjia kinship's adaptability to changing social environments while upholding its fundamental cultural values, underscoring its resilience in the face of outside challenges. This research advances our knowledge of indigenous kinship systems by exploring the cognitive aspects of Birjia kinship. It provides insightful advice on protecting and reviving cultural heritage in marginalized communities across the globe.