So I have been looking through a book by a Korean cartoonist where he tries to explain Korean culture and history, often going into the histories of the surrounding nations. However, it seems to be quite biased towards justifying various modern behaviours rather than giving a well-researched view of history, so I have some questions.

So my understanding from of the book is implying is that the Joseon Empire lasted from about 1400 to 1897, and during this time Korea was a sort of de facto vassal of China, paying tribute and having its foriegn affairs controlled by China, but also staying quite insular, and limiting transfer of people and culture. Japanese influence ended this stage, allowing the Empire of Korea to form, but now that Korea was free from Chinese protection, this permitted the Japanese to annex Korea.

However, a reading of wikipedia seems to contradict this a little. I don't find the word "vassal" anywhere on the Joseon page, and it seems like Korea's "hermit" policies were not until quite late (~19th century). I'm left not being clear on what the relationship between China and Korea was during this stage, or even what Japan's role and intentions were in allowing the creation of the Empire of Korea.

Now I know we're talking at a period of over 500 years, but could someone breifly summarise what exactly was going on - specifically, how dominant was China in Korean affairs at what stage? And what was Japan's role in bringing about the end of this period?