Nagarjuna attacked the metaphysics of the Sarvastivada school and a school which broke away from it called Sautrantika, and promoted, among other things, the classical emphasis on the dependent arising of phenomena of the early texts. The first sutra source which mentions the "three turnings" is the "Ārya-saṃdhi-nirmocana-sūtra" or "Noble sūtra of the Explanation of the Profound Secrets," the most foundational sutra of the Yogācāra school. The sūtra affirms that the earlier turnings while being authentic are also flawed or incomplete and require interpretation. The "Saṃdhi-nirmocana" further claims that its teachings are the ultimate and final truth. Major ideas include the basis-consciousness ("ālaya-vijñāna"), and the doctrine of cognition-only ("vijñapti-mātra") and the "three natures" ("trisvabhāva"). Some Buddhist traditions also consider the "Tathāgatagarbha" (also known as Buddha nature) teachings as part of this turning. This was elaborated on in great detail by Maitreya via Asanga in the Five Treatises of Maitreya, which are also generally grouped under the third turning. The Yogachara school reoriented later refinements, in all their complexity, so as to accord with the doctrines of earliest Buddhism. In Tibetan Buddhism, Buddhist tantra and its associated scriptures are sometimes considered to also be part of the third turning. Vajrayana schools sometimes refer to Buddhist tantra as the "fourth turning." As explained by Lama Surya Das, some traditions consider Dzogchen as a fourth turning. According to Japanese scholar Junjirō Takakusu, the Sanron (Sanlun) Madhyamaka school divided the teaching into three dharmacakras as well, but with different definitions for each:   The Chinese Tiantai school organized the Buddhas teachings into five periods (五時):   Likewise, the Huayen school had a five period system of dharma teachings:   The schema of the three turnings is found in Yogachara and Tathāgatagarbha texts such as the Saṃdhinirmocana Sūtra and the Srimala Sutra and likely originated in the Yogachara literature.