Gate of the Four Heavenly Kings
In Buddhist cosmology, the four Heavenly Kings (one for each cardinal direction) each rule over one slope of Sumi Mountain, situated at the center of the first of six heavens. The belief in these deities originated in India and was transmitted across Central Asia, and the appearance of the sculptures or carvings in each region also varies greatly. In Silla, the figures lost the frightening quality they sometimes had in other locales.
The Heavenly Kings permit goodness to pass while barring the entrance of evil into the temple. In passing through this gate, one symbolically moves from the profane world beneath heaven to the sacred heavenly realm.
*The Western Heavenly King, Kwangmok (Skt. Virupaksha)
The full name of the western Heavenly King means "dirty" or "evil eye." His common name, however, means "broad eye": wide-seeing one. The Kwangmok figure at Bulguksa holds a writhing dragon in one hand and a jewel in the other. The jewel is said to symbolize the world, and the western King acts to prevent its theft by the dragon.
*The Northern Heavenly King, Tamun (Skt. Vaisravana)
The name of this Heavenly King means "many-hearing Heavenly King": he who, from his place on the northern slope of Sumi Mountain, has heard more of Buddha's teachings than anyone else. This king holds a tower or stupa in his hand. One interpretation has it that the base represents suffering and the roof enlightenment, with the connecting section symbolizing Buddha's teachings that assist one in moving from one to the other. There is also a more conventional axis mundi interpretation, in which the base represents earth and the roof represents heaven.
*The Southern Heavenly King, Chungjang (Skt. Virudhaka)
This king's name means "repeatedly-expanding or growing Heavenly King." The sword this guardian carries is said to multiply according to the number of his enemies. In legendary accounts, Chungjang is sometimes depicted as carrying both a sword and a lance, but in most temple carvings (including the one at Bulguksa) he has only the former.
*The Eastern Heavenly King, Chiguk (Skt. Dhritarashtra)
The name of this figure means "the Heavenly King who holds (or protects) the nation." From the eastern slope of Sumi Mountain, he keeps the kingdom safe and eases the life of the ordinary people. In textual accounts his accoutrements vary, but at Bulguksa and elsewhere he is depicted as carrying a Pip'a, a sort of Korean lute or mandolin. Through playing this instrument, he is said to be able to control the weather.