Tattvasaṃgraha Tantra
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The Sarvatathāgatatattvasaṃgraha sutra (Sanskrit, Compendium of the Reality of All Tathāgatas), also known as the Tattvasaṃgraha Tantra, is an important seventh century Indian Buddhist tantric text.
Although the scripture refers itself as a Mahayana sutra, the content is mainly tantric in nature and thus is sometimes called a tantra.
This work is an important source for the Shingon tradition.