Huayan
Huayan is a major Chinese school of Buddhism which flourished in the Tang period.The Flower Garland school, one of the major schools of Chinese Buddhism, the doctrines of which ended up having profound impact on the philosophical attitudes of all of East Asian Buddhism. Established during the period of the end of the Sui and beginning of Tang dynasties, this school centered on the philosophy of interpenetration and mutual containment which its founders perceived in the Huayan jing (華嚴經). Yet despite basic reliance on this sutra, much of the technical terminology that the school becomes famous for is not found in the sutra itself, but in the commentarial works of its early founders.
The founding of the school is traditionally attributed to a series of five "patriarchs" who were instrumental in developing the schools doctrines. These five are: Dushun (杜順), Zhiyan (智儼), Fazang (法藏), Chengguan (澄觀) and Zongmi. Another important figure in the development and popularization of Huayan thought was the lay scholar Li Tongxuan (李通玄). Some accounts of the school also like to extend its patriarchship earlier to Aśvaghoṣa (馬鳴) and Nāgārjuna (龍樹).
Although there are certain aspects of this patriarchal scheme which are clearly contrived, it is fairly well accepted that these men each played a significant and distinct role in the development of the school: for example, Dushun is known to have been responsible for the establishment of Huayan studies as a distinct field; Zhiyan is considered to have established the basic doctrines of the sect; Fazang is considered to have rationalized the doctrine for greater acceptance by society; Chengguan and Zongmi are understood to have further developed and transformed the teachings.
After the time of Zongmi and Li Tongxuan the Chinese school of Huayan generally stagnated in terms of new development, and then eventually began to decline. The school, which had been dependent upon the support it received from the government, suffered severely during the purge of 841-845, never to recover its former strength. Nonetheless, its profound metaphysics, such as that of the four dharmadhātu (四法界) of interpenetration, had a deep impact on surviving East Asian schools, especially the Chan school.
See also the Hwaeom school of Korea, and Kegon school of Japan.
