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founding a country
opening of a country (e.g. Japan) to the world; ending (a policy of) national seclusion
ペリー来航により、日本はついに開国した。
With Perry's arrival, Japan finally opened its country.
開国後の社会は激動の時代を迎えた。
The society after opening the country entered an era of great upheaval.
列強からの圧力で、幕府は開国せざるを得なかった。
Under pressure from the great powers, the shogunate had no choice but to open the country.