UNESCO World Heritage Tentative List

UNESCO has included Odisha’s ‘Diamond Triangle’ of Ratnagiri, Udayagiri and Lalitagiri Buddhist sites in India’s tentative list for World Heritage Site status.

About the ‘Diamond Triangle’

• Constituent Sites: The Buddhist Diamond Triangle refers to a serial cultural cluster of three major Buddhist monastic–stupa complexes in Odisha—Lalitgiri, Udayagiri, and Ratnagiri.
• Location: The three sites are located in Jajpur and Cuttack districts of Odisha.
• Religious Significance: The sites are believed to have witnessed the propagation of all three major schools of Buddhism – Hinayana, Mahayana and Vajrayana.
• Origin of the Name: The term ‘Diamond Triangle’ is linked to Vajrayana (Tantrayana) Buddhism, where Vajra means thunderbolt or diamond.

Key Sites in the Diamond Triangle

Ratnagiri

• Meaning and Location: Ratnagiri literally means “Hill of Jewels”. It is located about 100 km northeast of Bhubaneswar, standing on a hill between the Birupa and Brahmani rivers.
• Archaeological Importance: Ratnagiri is Odisha’s most famous and most extensively excavated Buddhist site.
• Epicentre of Vajrayana Buddhism: It emerged as a major Vajrayana hub between the 4th and 12th centuries CE, particularly under the Bhaumakara dynasty.
• Archaeological Richness:
• • Excavations revealed a vast complex comprising a mahastupa, chaityagriha, monasteries, shrines, votive stupas and colossal Buddha heads. 
  • Sealings bearing the name “Sri Ratnagiri Mahavihariya” confirm its identity as a premier monastic university.
• Monastic Scale: At its peak, the monastery is believed to have housed around 500 monks, primarily following the Tantrayana form of Buddhism.
• Unique Architectural Feature: The Ratnagiri monastery is the only Buddhist monastery in India with a curvilinear roof.
• Hiuen Tsang: Studies suggest that Hiuen Tsang, who visited Odisha during 638–639 AD, might have visited Ratnagiri.

Lalitgiri

• Alternate Name: Known locally as Naltigiri.
• Antiquity: Lalitgiri, located on the Nandapahad hillock, represents the earliest Buddhist centre of the triangle, with uninterrupted occupation from the 2nd–3rd century BCE to the 13th century CE, making it one of the longest-lived Buddhist sites in India.
• Archaeological Discoveries::
  • Excavations by Utkal University and the Archaeological Survey of India (ASI) revealed an apsidal chaityagriha, four monasteries, and a massive Theravada stupa containing nested relic caskets of stone, silver and gold. 
  • The discovery of the inscribed seal referring to “Sri Chandraditya Vihara” confirms Lalitgiri’s status as an organised monastic institution.
• Key Archaeological Find: A relic casket comprising four containers made of Khondalite, Steatite, Silver and Gold, believed to contain relics of Lord Buddha.
• Doctrinal Evolution: Artefacts and sculptures of Buddha, Avalokiteswara, Vajrapani, Manjusri, Tara and Jambhala attest to Lalitgiri’s evolution across Theravada, Mahayana and Vajrayana, demonstrating early doctrinal synthesis and artistic experimentation

Udayagiri

• Location:
  • Known as the “Sunrise Hill”, Udayagiri is the largest complex in the triangle, situated on a crescent-shaped hill along the Birupa river. 
  • It flourished from the 1st to the 13th century CE as a major centre of Buddhist learning.
• Major Monastic Establishments: ASI excavations uncovered the Madhavapura Mahavihara and Simhaprastha Mahavihara, featuring large brick-built monasteries, a double-storeyed structure, pradakshinapatha, vaulted windows and an upper shrine chamber, rare features in Indian Buddhist architecture
• Artistic and Ritual Significance:
  • The site contains a massive chaityagriha showing architectural evolution from circular to apsidal to rectangular forms, housing Pancha Dhyani Buddhas. Numerous sculptures of Tara, Manjusri, Avalokiteswara, Maitreya and Vajrayana deities highlight Udayagiri’s role as a bridge between Mahayana and Vajrayana traditions

World Heritage Sites (WHS)

• World Heritage Sites are places of Outstanding Universal Value (OUV), recognised for their cultural, natural, or mixed significance and protected for the benefit of present and future generations.
• Legal Framework: These sites are safeguarded under the 1972 UNESCO World Heritage Convention, adopted by UNESCO member states to promote global heritage conservation.
• Governing Body: The UNESCO World Heritage Committee maintains and updates the World Heritage List through the World Heritage Programme.
• India and the Convention:
• • India ratified the World Heritage Convention in 1977, committing itself to the identification, protection, and conservation of heritage sites.
  • As of September 2025, India has 44 UNESCO World Heritage Sites, with the Maratha Military Landscapes of India being the most recent (44th) inscription.

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Tentative List 

• Definition: A Tentative List is an official inventory of cultural and natural sites that a State Party intends to consider for future nomination to the UNESCO World Heritage List.
• Role: Inclusion in the Tentative List is the first mandatory step towards World Heritage inscription. 
  • Only sites that appear on this list are eligible to be formally nominated for World Heritage status.
• Process: Once a site is included in the Tentative List, the State Party prepares a detailed nomination dossier, which is then examined and decided upon by the UNESCO World Heritage Committee.
• India’s Tentative List Status
  • Total Sites: India currently has 70 sites on UNESCO’s tentative list.
  • Categories Covered: The sites fall under cultural, natural and mixed categories.
  • Odisha Sites on Tentative List: Includes Ekamra Kshetra of Bhubaneswar and Chilika Lake in Ganjam district.
  • Recent Additions: The Chausathi Yogini group of temples, including sites in Odisha, was added last year.
    • Odisha hosts two Chausathi Yogini temples—near Bhubaneswar and in Balangir

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