This paper makes analysis of many materials regarding siddhapithas such as Uddiyana, Jaladhara, Kamarupa, Sriparvata, Vajrasana, Vikramasila and Uddantapuri, and points out that in the early days of the Buddhist Vajrayana in India, the practice centers were mainly in outlying areas, and in the later period, they were mainly in Bihar. The earlier centers were the sources of Tantric Sadhana and those in the later period were places that refined and polished Tantric books.
