Why did the Tokugawa shogunate keep Japan isolated from 1603 until 1853?

Answer 1

http://www.google.com/search?q=Tokugawa+shogunate&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

Fear of foreign influences? Read some of the articles to find out.

Answer 2

This site will help you with that.

http://www.wsu.edu/~dee/TOKJAPAN/SHOGUN.HTM