The historical development of Esoteric Buddhism in India is still known only in outline. A few verifiably early texts do give some insight into the origin of the ideas which would later develop and spread to East and Southeast Asia, and to Tibet. However, there is another kind of evidence which can be harnessed to the project of reconstructing the history of Esoteric Buddhist doctrines and practice. This evidence consists of art objects, mainly sculpture, which survive in significant numbers from the 6th to the 13th century.