What we know about Tantra or Tantrism today, comes from Buddhism and Hinduism, from the first centuries of the first millennium a.C.
The teachings contained in the Tantras are doing similar to the Agamas of the Shaivas and the Samhitas of the Vaisnavas, dedicated to the cosmic feminine principle, to Shakti.
The Goddess cult is present in many Tantric schools and already existed at the beginning of the Vedic epoch.
It seems that the first Hindu Tantras were lost, and we only know them through references made in other works, and they refer to 28 Tantras.
The typical original Tantra is presented in the form of a dialogue and is not attributed to any human author, but to the Divinity itself.
Since Tantrism, Hindu or Buddhist, is a broad, complex, and virtually unexplored field of study, I will confine myself here to the Hindu Tantras, which most immediately concern the yogic tradition that was born in the Vedic legacy.
Hindu tradition states that there are 64 Tantras, but the true number of these works is much greater.
Tantra is continuity, according to the ancient Buddhist text Guhya-Samâja-Tantra. Derived from the root “Tan”, which means “to extend”, “to stretch”. It is commonly interpreted as “that by which knowledge or understanding expands or spreads”.
One of the secondary meanings of Tantra is simply “book” or “text”, as in Panca-Tantra, which is a famous Indian collection of fables. Thus, Tantra can be defined as a text that expands understanding to the point of allowing the birth of true wisdom.
Wisdom is liberating because it establishes the tantra practitioner in the continuity that exists between finite and infinite dimensions, where liberation is not about leaving the world behind or eliminating one's own natural impulses, making integration the main characteristic of Tantra. The integration of the Self with the Self, of corporeal existence with spiritual reality.
Tantrism is intensely practical, so Yoga is the central element.
The teachings of Tantra are marked by an admirable synthesis of theory and practice, based on a vibrant eclecticism with a strong tendency towards ritualism. These teachings were tailored to meet the needs of the dark age, after the death of Lord Krishna at the end of the battle recounted in the epic Mahâbhârata, for those who are unable to direct their aspirations to God and are easily distracted by their ideas and conventional expectations.
With emphasis on the cult of the Goddess and ritual sexuality, Tantrikas, practitioners of Tantra, rejected the orthodox Hindu and Buddhist purist attitude, and sought to anchor the spiritual search in the corporeal reality, and there sexuality was introduced.