This is a set of an inner and outer case. Component analysis has
revealed that the outer case was made of a mudstone consisting of
sand particles, a stone material produced in large quantities in Pohang,
Gyeongsangbuk-do Prvince. Traces of clay slip and cinnabar have
been identified on the surface of the outer case, suggesting that it
originally featured decorative designs. The cases are an important
material for the study of the burial practices of the Goryeo royal court.