During the Edo period, Japan closed its country border and did not trade with foreign nations except for China, Korea and the Netherlands. All ships from overseas had to stay in Nagasaki and all non-Japanese had to live in a small island dedicated to only foreigners. Japanese were banned from visiting foreign countries and local feudal lords were not allowed to build ships. Only boats were allowed to be made for domestic transportation.
In the 16th century, Spanish and Portuguese ships with Catholic priests were sent to Japan to spread Christianity. Some local warriors allowed the spread of Christianity because the trading with western countries accompanied with Christianity brought them a lot of profit. However, rulers gradually began to realize that the principle of Christianity contradicted with their way of governance and as a result banned the religion. They were also worried about being colonialized like some of the South American and African countries. Historically Japan had relationship with China and Korea which share many cultural aspects, and therefore, the trading with these countries were kept. The Netherlands were selected as the only western trading partner as it was a Protestant country and it was believed that it had no intention to spread Christianity or to colonize Japan. Also, the Netherlands had such power at the time in Eastern Asia and Japan wanted to be protected from the invasion of other western countries. In the beginning of Edo Period, Britain was also participating in the trade but it soon came to a halt as trading with Japan was not profitable for Britain.
Over the 250 years, Japan has been isolated from rest of the world. Only limited information brought from the Netherlands and China kept Japan informed of what was happening in other parts of the world. The negative affect of isolation policy is, of course, that Japan was kept behind the development of science and democracy that bloomed in the western culture during that time. However, there were some positive effects from the isolation policy too. And they played an important role in forming today’s Japanese culture.