The Buddhist Tantras are a varied group of Indian and Tibetan texts which outline unique views and practices of the Buddhist tantra religious systems.
Buddhist Tantric texts began appearing in the Gupta Empire period  though there are texts with elements associated with Tantra that can be seen as early as the third century. By the eighth century Tantra was a dominant force in North India and the number of texts increased with numerous Tantric pandits writing commentaries.
The earliest known datable Buddhist Tantra is possibly the Guhyasamāja Tantra which is dated to the fifth century by Alex Wayman (but to the eighth by Japanese scholars). Another early Tantra is the Mahavairocana Tantra, which was mentioned and collected by the Chinese pilgrim Wu-xing (無行) c. 680 CE.
According to Tibetologist Alex Wayman, the Buddhist Tantras arose from "a previous lore reaching back into the Vedic literature and amalgamating this tradition with various Buddhist tenets". Some of the material is also similar to content in the Yoga Upanishads. Buddhist Tantric traditions were variously influenced by Śaiva and Pancharatra Hindu traditions, local god/goddess cults, Yaksha or nāga rites as well as drawing on pre-existing Mahāyāna Buddhist ideas and practices.
Many early Buddhist Tantric texts, later termed “action Tantras” (kriyā tantra), are mostly collections of magical mantras or phrases for mostly worldly ends called mantrakalpas (mantra manuals) and they do not call themselves Tantras. Later Tantric texts from the eighth century onward (termed variously Yogatantra, Mahayoga, and Yogini Tantras) advocated union with a deity (deity yoga), sacred sounds (mantras), techniques for manipulation of the subtle body and other secret methods with which to achieve swift Buddhahood. Some Tantras contain antinomian and transgressive practices such as ingesting alcohol and other forbidden substances as well as sexual rituals. Some of the unique themes and ideas found in the Buddhist Tantras is the revaluation of the body and its use in attaining great bliss (mahasukha), a revaluation of the role of women and female deities and a revaluation of negative mental states, which can be used in the service of liberation as the Hevajra Tantra says "the world is bound by passion, also by passion it is released".
Buddhist Tantra quickly spread out of India into nearby countries like Tibet and Nepal in the eighth century, as well as to Southeast Asia. Buddhist Tantra arrived in China during the Tang Dynasty (where it was known as Tangmi) and was brought to Japan by Kukai (774–835), where it is known as Shingon. It remains the main Buddhist tradition in Nepal, Mongolia and Tibet where it is known as Vajrayana.
There are between 1500 and 2000 surviving Indian Buddhist Tantric texts in the original Sanskrit, and over two thousand more Tantras solely survive in translation (mostly Tibetan or Chinese). In the Tibetan canons, there are 450 Tantras in the Kanjur collection and 2400 in the Tengyur.
Tantric texts were brought to Tibet in two historical periods, the 8th century and the 11th century. The ancient translation school, or Nyingma and the later New translation schools organize Tantras into different categories.
Many Tantric texts have titles other than 'Tantra', including Dharani, Kalpa, Rajñi, stotra, doha and sutra. The Major Tantras also accumulated secondary literature, such as 'Explanatory Tantras' (vyākhyātantra), commentaries and sadhana literature. Major Buddhist Tantric texts include:
As Buddhist Tantra became more widely practiced in the middle of the seventh century, pandits at mainstream Buddhist scholastic institutions began to adopt the practices and write sadhanas and commentaries on Vajrayana praxis. Benoytosh Bhattacharyya notes that there are two main chronological lists of prominent Tantric authors, the first from Taranatha's works and the second from Kazi Dawasamdup's introduction to the Cakrasaṃvara Tantra.