The Korean ancestors had invented and developed the metal casting technology from the ancient times to produce many elegant bells. Bells graceful in shape, excellent in decoration and beautiful in sound were hung in different parts of Korea including the Pongdok Temple.

In the middle ages, Japan was too backward in civilization to make excellent bells like the Korean ones by its own effort.

The Japanese aggressors, who started their overseas aggression from early years, frequently sneaked into Korea to steal Korean bells.

Of the Korean bells plundered by the Japanese aggressors, more than 10 bells were recast with letters and more than half of them were carved from 1367 to 1381. This shows that the plunder of Korean bells by the Japanese aggressors became blatant in the last period of Koryo (918-1392).

The Japanese aggressors' plunder of Korean bells got more pronounced during the Japanese aggressors' invasion of Korea (1592-1598).

As a result, the bells associated with the wisdom and talents of the Korean ancestors were not many left.

Even the Japanese did not conceal the fact that there were more Korean bells in Japan than in Korea. Ryosaku Hujita, a part-time employee of a department for historic remains survey of the "government-general in Korea" during the Japanese imperialists' military occupation of Korea (1905-1945), wrote in an article titled "Koryo Culture" that the Korean bells which became treasures of Japan were all temple bells of Koryo and there were not many left in Korea.

Still now, Japan has set many Korean bells as its "national treasures", insisting that they belong to it.

All the facts reveal the history of Japan's deep-rooted aggression and plunder over Korea.