Chengquan (澄观), a prominent monk of the Tang Dynasty, authored the "Commentary on the Huayan Sutra" (华严疏), a seminal work in the Huayan school of Buddhism. Zongmi (宗密), also a Tang Dynasty monk and disciple of Chengquan, wrote the "Annotations to the Commentary on the Huayan Sutra" (别行疏), further elaborating on Huayan philosophy.