The main functions of a Buddhist temples are as a place for Buddhist services and a place for sermons and each ancient Buddhist temple was equipped with a main and separate building. After Zen Buddhism was first introduced, there was a tendency to change the terms to Buddhist sanctuary and altar, as set forth in the Zen Buddhism code of conduct called 'Cheonggyu(淸規)'. As such, it was thought that the division between Buddhist service space and preaching space were relatively firm until the Goryeo Dynasty. However in the period from the end of the Goryeo to the beginning of the Joseon Dynasty there was an increasing tendency of integration of the two buildings. It can be seen that, in cases where both buildings remained, statues of Buddha were enshrined in these buildings without any distinction. Eventually it is led to the tradition of duo-Buddhist sanctums.