The many monks who did study in China had a broad impact on the religious culture of the Korean peninsula. In fact, there were at least five main sects of Buddhism being practiced in Silla during this period: Kyeyul, Yulban, Chinpyo, Popsong, and Hwaom. Chinpyo and Popsong were introduced by Won-Hyo with Popsong, being based upon Hwajong-non (Treatise on the Harmonious Understanding of the Ten Doctrines) from which Won-Hyo's posthumous title of "Hwajong Kuksa" was derived. Won-Hyo was, in fact, the most influential of the many monks of the 7th century. He used his power in an attempt to unify the five existing sects and reduce their constant sectarian rivalries.
Won-Hyo is also considered to be one of the most prolific writers in all of the Buddhist countries of his time, his works include over 100 different kinds of literature consisting of about 240 volumes. Unfortunately, only 20 works within a total of 25 volumes have survived. One of the forms he chose to use was a special Silla poetic form, Hyang-Ga. These poems were mainly written by monks or members of the Hwarang and concerned patriotism, Buddhism, and praise of the illustrious dead. Won-Hyo's poem "Hwaorm-Ga" is said to be among the most admired of these poems.
Won-Hyo's writing was not the only area in which he gained recognition. He was well known both to the general population and to the members of the royal family and their court. He was often asked to conduct services, recite prayers, and give sermons at the royal court. In 660 AD, King Muyo became so interested in Won-Hyo that he asked him to come and live in the royal palace of Yosok. Won-Hyo developed a relationship with the royal princess Kwa, which was soon followed by their marriage and the birth of their son Sol-Chong.