The Seongjusan sect was located out of present-day Boryeong, Chungcheongnam-do at Seongjusa Temple. According to Prof. David Mason, this temple was already established in 616 A.D. through the orders of King Mu of Baekje (r. 600-641 A.D.). The temple was originally named Ohapsa Temple. The reason for this name was to help commemorate the recent victory over the neighbouring Silla and to pray for the souls of soldiers that had died during the conflict. As Prof. Mason points out on his website, “The Samguk-Yusa records that in 659, during the reign of the final King Uija (의자왕), a ‘Red Goblin’ (hong dokkebi) was seen circumambulating this temple 6 times (an inauspicious number), and then announced a prediction that Baekje would soon collapse (it did so just a year later, under attack from Tang China and Shilla).”
Then, in 845 A.D., Kim Yang (808-857 A.D.), a local aristocrat asked King Munseong of Silla (r. 839-857 A.D) to appoint Master Muyeom (801-888 A.D.) as the abbot of the already important temple. It was only after the king provided funds for the renovation and expansion of the temple that it changed its name from Ohapsa Temple to that of Seongjusa Temple, or “Saint Abides Temple” in English.
As for Master Muyeom, his family name was that of Kim, and he was the eighth generation descendant of King Muyeol of Silla (r. 654-661 A.D.). His mother was from the Hwa clan. Muyeom first became a monk at Osaekseoksa Temple in present-day Yangyang, Gangwon-do. He learned the dharma under Beopseong-seonsa. Later, Muyeom lived at Buseoksa Temple, where he studied the Hwaeom doctrinal teachings. In 821 A.D., Muyeom traveled to Tang China (618–690, 705–907 A.D.) and visited the monk Magu Baozhe (720-?), who learned under Mazu Daoyi (709-788 A.D.). It was from him that he received formal recognition in the Seon teachings. Afterwards, people called Muyeom the “Bodhisattva of the Eastern Region [Dongbang-bosal]. In 846 A.D., Muyeom returned to Silla after being requested to return by Prince Kim Heun (803-849 A.D.). Muyeom resided at Ohapsa, which then became Seongjusa Temple (as was previously mentioned).
Muyeom served as the national preceptor during the reigns of two kings, King Gyeongmun of Silla (r. 861-875 A.D.) and King Heongang of Silla (r. 875-886 A.D.). Muyeom would remain active in Silla politics; and in fact, he would teach the two kings Seon Buddhism which helped strengthen the popularity of this new form of Buddhism. Muyeom would die in 888 A.D. His posthumous name was Daenanghye. Among his disciples were Sunye, Wonjang, and Yeongwon. In total, some two thousand people became monks under him. So Seongjusa Temple became central to the propagation of Seon Buddhism throughout Silla. And Seongjusa Temple would continue to flourish through the Goryeo Dynasty (918-1392) up until the Joseon Dynasty (1392-1910), when it was destroyed during the Imjin War (1592-98).