Yixing belonged to the northern school of Chán Buddhism, but this was not seen by Chinese Buddhist culture as being fundamentally different from the esoteric teachings of Śubhakarasiṃha.
It is first found in Chinese texts, related to Chinese Tantric Buddhism, which was centred on the Buddha Vairocana and propagated by the three great masters Śubhakarasiṃha, Vajrabodhi, and Amoghavajra.