Thus, at the time when Nagasaki silver exports had fallen considerably, seven times as much silver-about 8,000 kilograms a year-left Tsushima for Korea than from Nagasaki. Virtually all of this silver ended up in China, its total amount rose up through the late 1660s, and it continued to leave Japan through these routes in similar figures up into the middle of the eighteenth century.

     Also, when we expand our view from silver to all precious metals, we see how the same years silver exports dropped also saw a significant increase in the amount of copper exports. While not as heatedly demanded or as lucrative as the silver trade, the copper trade constituted as much as 90% of the value of Dutch exports from Japan during the period 1677 to 1710. Copper exports to China also increased greatly during the 1680s and 1690s, rising by the end of the century to as much as four times their amount in 1668, the year of the first ban on silver exports. While they did not have the same value as silver, they did meet, in the view of one student of early Qing monetary policy, the copper coin needs of the China mainland at this time and partly made up for the drop in the export of silver.

     Thus, even in the case of silver, the drop in exports from Nagasaki came three decades after the implementation of the "national seclusion" policy. It was ameliorated by silver exports from other Japanese ports, and it was replaced to some extent by copper exports. The Tokugawa government thus was not aiming to cut the country's exports but rather to control the passage of people and ideas in and out of the country. Yes, the Tokugawa government prevented Japanese merchants from traveling abroad and foreign merchants from trading inside Japan. But it did not refuse to support the export of certain Japanese goods and the import of certain foreign goods. Instead, it actively encouraged their departure in ways radically different from previous policies. For its underlying economic principle was economic restructuring. East Asians can identify this policy as in accord with traditional Chinese and Japanese ideas about the economic autarchy of a state, and Westerners can probably label it mercantilist. But a more economic understanding of what happened in late seventeenth and early eighteenth century Japan would stress the switch of Japan's exports from raw materials like silver to manufactured products like ceramics and silk. The Japanese succeeded in fostering suitable domestic substitutes for imported products. This government policy leading to what economists would call import substitution significantly altered Japan's economic relationship with East Asia and the rest of the world well before its policy of national seclusion ended in 1868. In 1715, the Tokugawa shogunate restricted the annual number of Chinese ships allowed to visit Nagasaki to just 30, and just 2 for the Dutch.