Yi Xing
Indian Tantric Buddhist philosophers such as Buddhaguhya, Vimalamitra, Ratnākaraśānti and Abhayakaragupta continued the tradition of Buddhist philosophy and adapted it to their commentaries on the major Tantras. Abhayakaragupta's "Vajravali" is a key source in the theory and practice of tantric rituals. After monks such as Vajrabodhi and Śubhakarasiṃha brought Tantra to Tang China (716 to 720), tantric philosophy continued to be developed in Chinese and Japanese by thinkers such as Yi Xing and Kūkai.