Japan's isolation began right before the Tokugawa Shogunate began, and the first Europeans were ariving in Japan.  They brought items to trade with the Japanese for their gold and silver.  Then, in 1549 Catholic churches were ariving in Japan.  In 1614, the Japanese converted to Christians.  In the 1630's, Tokugawa Ieyasu was worried about the foreigners in Japan.  He had heard about a Spanish settlement in the Philippines.  He ordered all Christians to leave Japan ,and if they came back to Japan they'd be killed.  He also banned most European trade and freed Japan of European influences