The stone-joint metal clamps, called ‘eun-jang’ in Korean and ‘yao-tie’ in China, is a time- honored structural reinforcement device, the appearance of which seems to have coincided with the advent of dry ashlar masonry in architectural history. Due to the high cost and the demand for skilled craftsmanship needed for the supply of ashlar stones and for the production of rust-proof metal clamps, the clamping device was mostly applied to the architecture and monuments built under the state and religious commissions in the ancient world. This is also the case in the early part(ca.668-800CE) of the Unified Silla period(668-935CE). Stone-joint clamps are found globally, but regional differences accord with the time of appearance and duration of usage depending on the developmental phases of stone architecture and geopolitical conditions in the given region or country. In ancient East Asia, as of now, China appears to have been the forerunner in using the device. The earliest known Chinese ‘ yao-tie’ specimens are from the stone mortuary furnishings of the 6th-century tombs. Prior to these excavations, the Zhaozhou Bridge of Sui-China(581-618CE) had been the best- known site.