This thesis explores the possibility of the Vedic deity, Soma, having its origins in the Indus Valley Civilization (2500 BCE–1900 BCE; also known as the Harappan Civilization). It presents the argument that the Indus Valley, through its shaping of Soma, indirectly affected Tantric texts and practices. What follows is an overview of theoretical positions of significant scholars who attempted to identify a yogic, horned figure on what is known as seal 420 from the Harappan Civilization. Unfortunately, these scholars have not provided an in-depth analysis of how the figure on seal 420 has impacted later forms of Hinduism. This work attempts to do this by postulating a connection between Soma the bull and the Harappan horned-figure; this connection is suggested by utilizing iconographical, archaeological and textual evidence. There is reference to Thomas McEvilley’s hypothesis of a sexo-yogic fertility ritual in the Indus Valley, and an argument is provided to support it by arguing for Soma’s association with sex, semen, and immortality. Again, this is done by using archaeological evidence and reconciling it with textual evidence that portrays the connections between Soma, the bull, fertility, seminal retention, and sexual drive. Lastly, by observing and analyzing South Asian Sanskrit sources dating from roughly 1500 BCE–1500 CE, the theory is put forward that Soma and its association with semen, fertility, immortality, and seminal retention has survived since the time of the Harappans and has influenced Tantric ritual since the eighth century CE.