Some port cities within Japan were selected, at different stages of the Tokugawa era, as outward-looking harbours.
Foreigners, allowed in from a restricted number of countries, usually resided within bounded quarters, and conducted their business under the strict supervision of the Tokugawa or of other local authorities.
Occasionally, trips to Edo were arranged for foreigners in escorted diplomatic missions. Members of the Dutch East India Company, for example, regularly sent missions from Nagasaki to Edo. Korean diplomats also occasionally travelled to the Tokugawa capital through Tsushima.
The ports functioned, in this sense, as bridges to the outside world –
a world that expanded rapidly at the end of the Tokugawa era, as Japan was pushed to establish commercial and diplomatic relations with a growing number of foreign powers.