both groups. He also states that the Śaiva tradition was also involved in the appropriation of local deities and that tantra may have been influenced by tribal Indian religions and their deities. Samuel writes that "the female divinities may well best be understood in terms of a distinct Śākta milieu from which both Śaivas and Buddhists were borrowing," but that other elements, like the Kapalika style practices, are more clearly derived from a Śaiva tradition. Samuel writes that the Saiva Tantra tradition appears to have originated as ritual sorcery carried out by hereditary caste groups (kulas) and associated with sex, death and fierce goddesses. The initiation rituals involved the consumption of the mixed sexual secretions (the clan essence) of a male guru and his consort. These practices were adopted by Kapalika styled ascetics and influenced the early Nath siddhas. Overtime, the more extreme external elements were replaced by internalized yogas that make use of the subtle body. Sexual ritual became a way to reach the liberating wisdom taught in the tradition. The Buddhists developed their own corpus of Tantras, which also drew on various Mahayana doctrines and practices, as well as on elements of the fierce goddess tradition and also on elements from the Śaiva traditions (such as deities like Bhairava, which were seen as having been subjugated and converted to Buddhism). Some Buddhist tantras (sometimes called "lower" or "outer" tantras) which are earlier works, do not make use of transgression, sex and fierce deities. These earlier Buddhist tantras mainly reflect a development of Mahayana theory and practice (like deity visualization) and a focus on ritual and purity. Between the eighth and tenth centuries, new tantras emerged which included fierce deities, kula style sexual initiations, subtle body practices and sexual yoga. The later Buddhist tantras are known as the "inner" or "unsurpassed yoga" (Anuttarayoga or "Yogini") tantras. According to Samuel, it seems that these sexual practices were not initially practiced by Buddhist monastics and instead developed outside of the monastic establishments among traveling siddhas. Tantric practices also included secret initiation ceremonies in which individuals would enter the tantric family (kula) and receive the secret mantras of the tantric deities. These initiations included the consumption of the sexual substances (semen and female sexual secretions) produced through ritual sex between the guru and his consort. These substances were seen as spiritually powerful and were also used as offerings for tantric deities. For