Generally speaking, China inherited the Mahāyāna Buddhism that existed in India before the Tang Dynasty in its entirety, whereas, following this time period, Tibet took over the non-Buddhist form that Indian Buddhism evolved into. After it flourished in India, Mahāyāna Buddhism gradually assimilated a large number of cultural elements from Hinduism, and, through this phenomenon of transculturation, it evolved into Tantric Buddhism, which became the prevalent philosophy of the Indian Buddha Dharma. These facts are attested by the archeological records uncovered at the ruins of the Nalanda Monastery and are also well evidenced by the bibliographies of Masters Xuanzang and Yiching.
At the time of Emperor Songtsän Gampo (around early Tang Dynasty), Tibet officially entered the era of writing and publication and profusely imported new cultural elements from India and China. The most impactful measure was certainly the installment of Buddhism as its state religion. After the Dark Age, Tibet adopted Tantric Buddhism from India almost in its entirety and incorporated some aspects of the local Bonpa religion therein. The dissemination of this practice by translation masters, such as Rinchen Bzangpo, during the period of the second propagation of Buddhism in Tibet helped establish the main structures of Tibetan Lamaism, which feature, in sequential order, Hīnayāna, Mahāyāna, Vajrayāna (Secret Mantra), and finally the attainment of Buddhahood in one single lifetime as its principal stages of cultivation.
The Tibetan Lamaist traditions that have existed since ancient times can be subsumed into two main systems based on their philosophical background: Tathāgatagarbha-Mādhyamaka and Prāsaṅgika-Mādhyamaka. The former system encompasses the following lineages: Nyingma, Kagyu, Sakya, Jonang, etc. It preaches about the Tathāgatagarbha, Svātantrika-Mādhyamaka, the Consciousness-Only view, the view of the non-duality of cyclic existence and nirvāṇa, the Great Middle Way, the view of other-emptiness, and so forth. Although these teachings are all based on the principle of “the non-existence of the conventional truth vs. the existence of the ultimate truth,” each school delineates the ultimate truth in a drastically different way. Separately, the doctrine of Prāsaṅgika-Mādhyamaka was popularized by Tsongkhapa, founder of the later-established Gelug tradition, as well as by his disciples over many generations. Boosted by its newly-acquired political predominance, the Gelug tradition’s endeavors thwarted the propagation of the thought pertaining to the class of the Tathāgatagarbha and led to a loss of talents in the related lineages. Up to present day, Prāsaṅgika-Mādhyamaka remains the prevalent thought within the Tibetan Lamaist philosophy. (Part 2)