Buddhism in Korea. Chinese Buddhism was officially introduced to Korea during the Three Kingdoms period (c.350–668) when the country was divided into Koguryŏ, Paekche, and Silla. The teachings were transmitted first to Koguryŏ, then to Paekche, both in the 4th cent. CE, and finally spread to Silla in the 6th cent. The new religion allied itself with the court, embraced indigenous shamanism and folk religion, gradually penetrating to the populace. Buddhism in Silla contributed to the formation of the Hwarang Do, a unique institution which trained young aristocrats in civil and military virtues, through devotion to Mirŭk (Maitreya Bodhisattva) and observance of Buddhist precepts.

During the unified Silla period (668–935) Buddhism took root and flowered in Korean soil. Many monks went to China and even to India in pursuit of Buddhist truth. The five major schools were formed: Yŏlban (Nirvāna), Kyeyul (Vinaya), Pŏpsŏng (Dharma-nature), Hwaŏm (Hua-yen), and Pŏpsang (Consciousness-only). In addition, the nine lineages (Nine Mountains) of Sŏn (Ch'an/Zen) were transmitted from China. However, Hwaŏm Buddhism played the crucial role: Wŏnhyo (618–86) and Ŭisang (625–702) contributed to making Silla Buddhism syncretic and nationalistic, traits which have since been the hallmarks of Korean Buddhism. Faith in Kwanŭm (Kuan-yin) was also widely held among the people.

The Koryŏ dynasty (935–1392) marks the zenith of Korean Buddhism. Buddhism absorbed religious Taoism and Buddhist esotericism; the halls of the seven stars (of the Dipper) and the halls of mountain gods were built along with the Buddha halls. Maṇḍalas of buddhas, bodhisattvas, and gods were painted. Two new sects were established in this period: the Ch'ŏnt'ae (T'ien-t'ai) sect, by Ŭich'ŏn (1055–1101), and the Chogye sect, by Chinul (1158–1210), through a unification of the nine existing Sŏn lineages. The publication of the Korean Tripiṭaka in the 13th cent. was a brilliant achievement of Koryŏ Buddhism. For all of this, Buddhism was plagued by increasing internal corruption and external discontent.

The rulers of the Yi dynasty (1392–1910), adopting Neo-Confucianism as the state orthodoxy, advanced a series of anti-Buddhist policies which dealt a crippling blow to Buddhism. King T'aejong (r. 1401–18) reduced the eleven existing sects to seven, and King Sejong (r. 1419–50) reduced those seven sects to just two: the doctrinal school (kyojong) and the meditational school (sŏnjong). The number of monasteries was drastically diminished.

During the period of Japanese rule (1910–45), Korean Buddhism, under the influence of its Japanese counterpart, made some reforms but also suffered serious set-backs. The two surviving Buddhist groups were forced in 1911 to merge with the Chogye sect. In 1919 countless Buddhists together with other religionists and patriots participated in the March First Movement against Japanese colonial rule.

Since Korea's independence in 1945, Buddhism has coped with the challenges of the modern world. Shedding its seclusion in deep mountains, it is nowadays active in the cities. The Chogye sect remains influential. Young people are involved in Buddhist studies, meditation, the monastic way of life, and social services. The activities of nuns are noteworthy. Won Buddhism is the most popular lay Buddhist movement today.