Noun
sakoku (uncountable)
(historical) The foreign policy of Japan between the 1630s and 1866, during which entry to and exit from Japan were severely restricted.
Perry had achieved his primary objective of breaking Japan’s sakoku policy and setting the grounds for protection of American citizens and an eventual commercial agreement. Source: Internet
Signed under threat of force, it effectively meant the end of Japan’s 220-year-old policy of national seclusion ( sakoku ), by opening the ports of Shimoda and Hakodate to American vessels. Source: Internet
This was the beginning of " sakoku ", where Japan was essentially closed to the western world until 1854. Source: Internet