After the shogunate closed Japan's ports and banned foreign travel and trade in 1638, for how many years?

Question:

Answer:

The isolationism was implemented step by step from the beginning of the Tokugawa Shogunate in 1603.
There is no fixed theory in what year the isolationism began. 1639 is one of the interpretations.
The end of the isolationism is fixed in 1854 when the Tokugawa Shogunate concluded the Treaty of Peace and Amity with the US.