how was japan isolated from the rest of the world
Sakoku Japan traded at this time with five entities, through four "gateways". The largest was the private Chinese trade at Nagasaki (who also traded with the Ryūkyū Kingdom), where also the Dutch East India Company was permitted to operate. The Matsumae clan domain in Hokkaidō (then called Ezo) traded with the Ainu people. Through the Sō clan daimyō of Tsushima, there were relations with Joseon-dynasty Korea. Ryūkyū, a semi-independent kingdom for nearly all of the Edo period, was controlled by the Shimazu family daimyō of Satsuma Domain. Tashiro Kazui has shown that trade between Japan and these entities was divided into two kinds: Group A in which he places China and the Dutch, "whose relations fell under the direct jurisdiction of the Bakufu at Nagasaki" and Group B, represented by the Korean Kingdom and the Ryūkyū Kingdom, "who dealt with Tsushima (the Sō clan) and Satsuma (the Shimazu clan) domains respectively".[2]