I think this question most likely refers to the period of Sakoku, which lasted between 1630s and 1860s. It was a period of isolation of Japan, with very minimal contact to the outside world.
One result of this policy was that Japan has retained its culture throughout this period, because it did not have an outside influence.
Another result was that Japan escaped western imperialism, which other countries in the region did not (and so Britain for example established a colony in Hong Kong)
