Synopsis Main objective of this study is to frame a tantric image in the historical development of Buddhist theo-philosophy and its impacat on Buddhist communities in India and other Buddhist countries. Here, I intend to recover the missing links in the history of tantric thoughts through an investigation of the theoretical and practical situations of two important texts which fall between the Tattvasamgraha-tantra and the Hevajra-tantra, that is, the Guhyasamaja-tantra and the Sarvabuddha-samayogadakini-maya samvara-tantra. My investigation will center upon the practice of svadhidaivatayoga (union with a specific deity of a mondala) which is assumed to be prevalent in the whole course of Tantric Buddhism.