The Huayan school of Buddhism (, Wade-Giles: Hua-Yen, "Flower Garland," from the Sanskrit "Avataṃsaka") is Mahayana Buddhist tradition that developed in China during the Tang dynasty (618-907). The Huayan worldview is based primarily on the Buddhāvataṃsaka Sūtra (, Flower Garland Sutra) as well as on the works of Huayan patriarchs, like Zhiyan (602–668), Fazang (643–712) and Zongmi (780–841).
Another common name for this tradition is the Xianshou school (Xianshou being another name for patriach Fazang). The Huayan School is known as Hwaeom in Korea, Kegon in Japan and Hoa Nghiêm in Vietnam.
The Huayan tradition considers the Flower Garland Sutra to be the ultimate teaching of the Buddha. It also draws on other sources, like the Mahayana Awakening of Faith, and the Madhyamaka and Yogacara philosophies. Huayan teachings, especially its doctrines of universal interpenetration, nature-origination (which sees all phenomena as arising from a single ontological source), and the omnipresence of Buddhahood, were very influential on Chinese Buddhism and also on the rest of East Asian Buddhism. Huayan thought was especially influential on Chan (Zen) Buddhism, and some scholars even see Huayan as the main Buddhist philosophy behind Zen.
The Avataṃsaka Sūtra is a compilation of sutras of various length, which originally circulated as independent sutras before being combined into the "full" Avatamsaka. One of the earliest of these texts, the Ten Stages Sutra, may date from the first century CE. These various sutras were probably joined together shortly before its translation into Chinese, at the beginning of the 5th century CE.
There are various versions of the Chinese Avatamsaka sutra (Huayan sutra). The full sutra was translated into Chinese three times (in versions of 40, 60, and 80 fascicles). The earliest Chinese texts associated with the Avatamsaka sutra are the Dousha jing (Taisho 280), produced by Lokaksema in the latter part of the second century CE, and the Pusa benye jing (T. 281), translated by Zhi Qian in the early to mid third century.