Ratnagiri was once the site of a mahavihara, or major Buddhist monastery, in the Brahmani and Birupa river valley in Jajpur district of Odisha, India. It was part of the Puspagiri University, together with Lalitgiri and Udayagiri. Ratnagiri was established no later than the reign of the Gupta king Narasimha Baladitya in the first half of the sixth century CE, and flourished until the twelfth century CE. A Tibetan history, the Pag Sam Jon Zang, identifies Ratnagiri as an important center in the development of the Kalachakratantra in the 10th century CE, an assertion supported by the discovery of a number of votive stupas, plaques, and other artifacts featuring Kalachakra imagery