The Japanese had long tried to cultivate insam on their soil but in vain.

After the emergence of "Korea-Japan Defence Provisions", called "Kanghwa Island Treaty", in 1876, an endless stream of Japanese sailed to Korea in groups to steal insam. Their robbery was done with the support of arms.

The Japanese even practiced smuggling of hongsam (steamed-and-dried insam), the export of which was prohibited by the Feudal Joson (Korea) Dynasty (1392-1910). They stole the hongsam manufacturing technique from Korea to produce hongsam in secret and sell them to China as Korea's.

They annually plundered 600 kilograms of hongsam, getting profit of 15,000 won.

At the beginning of its colonial rule, the Japanese government-general deprived the Korean royal government of its right to monopoly of insam, the nation's major revenue.

The Japanese invaders even had insam products named after the Japanese government-general, thus stripping Korea of the trademark right for insam.

Japan looted at least 11.58 million kilograms of Koryo insam between 1911 and 1942 alone.