Lalitagiri, Ratnagiri, Udayagiri: Odisha’s Diamond Triangle & Lost Vajrayana Legacy
The spatial geometry of Lalitagiri (northwest), Ratnagiri (northeast), and Udayagiri (south) as mapped by ASI in 1997–2000, revealing a deliberate 12-km triangular layout. The archaeological complex collectively known as the Diamond Triangle— Lalitagiri, Ratnagiri, and Udayagiri—represents the most concentrated evidence of post-Mauryan to Pala-period Vajrayana Buddhism outside the Gangetic heartland. Situated on the right bank of the Mahanadi deltaic system, these mahaviharas operated as a networked triad between the 2nd century BCE and 13th century CE , preserving textual, epigraphic, and iconographic data that illuminate the transition from Hinayana to Mahayana to Vajrayana in eastern India. This article synthesizes primary excavation reports (ASI 1958–2004), unpublished copper-plate grants, Pala-Sena numismatic correlations, and Tibetan canonical references to reconstruct the institutional history, doctrinal specialization, and eventual decline of these sites. Recent paleoclimat...