The lifetime of Master Naong Hyoegun (1320-1376) was a time of difficulty under the influence of the Yuan (元) Dynasty in China. Effort were made to repair the damage suffered by society and the Buddhist monastic commmunity at the end of Koryo Dynasty. Neo-Confucianists strongly criticized Buddhism.
While broadly spreading Master Dhyanabhadra's (指空) No-mind Son (無心禪) and Master P'yougsan Ch'orim's (平山處林) Linji Son, Master Naong had much interest in Pure Land Contemplation Son (浄土念彿禪) and taught his disciples and lay Buddhists accordingly. His thoughts mainly developed focusing on reciting the names of Buddha (称名念彿), Buddha Contemplation (観念念彿), and mind of Pure Land (唯心浄土). In particular, he composed the ‘Songwoka’ (僧元歌) of Kasa (歌辭), which was written in Korean language expressed in Chinese characters (I du munch'a 吏讀文字) in order for lay people to understand more easily. However, he did not present a koan method for Buddha Contemplation Son (念彿公案法). His Dharma song which begins with “Where is Amita Buddha (阿彌陀彿在何方)―” is always recited in liturgical services and the grand Buddha Contemplation ritual in Korea today, and it is generally recited as a representative Dharma song of Buddha-Contemplation Son (念彿禪).