More important in terms of Japan's relationship with the outside world, he ordered the country closed to Europeans. Christianity was outlawed and the missionaries were expelled. ... Closing the ports against “contamination” by Western ideas is often presented as evidence of Japanese backwardness.
The imperial ministers had much the same reasons as their counterparts in Japan for restricting foreign trade: religion and technology would disrupt the society and ultimately the government. ... Japan felt that it was the country of the gods and was therefore superior to Europe as well.