Korea and Vietnam used to be imperialized and colonized by China and that is how they adopted many of the Chinese cultural elements. On the other hand, Japan did the imperializing and colonization of areas in China and adopted cultural elements that way. Because Japanese soldiers and administrators were stationed in China during this time, they took Chinese wives and adopted their culture that way, but also just by living there. Once the time in Japan was over, the Japanese people took those cultural elements back home with them.