Since its arrival in America in the 1950s and the Dalai Lama's Nobel Peace Prize in 1988, Buddhism has been one of the fastest-growing religions in America and Tantra one of its most popular yet misunderstood forms. This work describes the historical origins of the Tantric movement in early medieval India. Drawing on primary documents - translated into English for the first time from Sanskrit, Prakrit and Bengali - Ron Davidson shows how changes in medieval Indian society, including economic and patronage crises, a decline in women's participation, and the formation of large monastic orders, led to the rise of the esoteric tradition in India that became the model for Buddhist cultures in China, Tibet and Japan.