The "Christian problem" is, in effect, a problem in control- ling both the Christian daimyo in Kyushu and trade with the Europeans.

By 1612 the shogun's retainers and residents of Tokugawa lands have been ordered to foreswear Christianity.

More restrictions come in 1616 (the restriction of foreign trade to Nagasaki and Hirado, an island northwest of Kyushu), 1622 (the execution of one hundred and twenty missionaries and converts), 1624 (the expulsion of the Spanish), and 1629 (the execution of thousands of Christians).

Finally, in 1635, an edict prohibits any Japanese from traveling outside Japan or, if someone leaves, from ever returning.

In 1636 the Portuguese are restricted to Deshima, a man-made islet—and thus, not true Japanese soil—in Nagasaki's harbor.