Why and how did korea pursue an isolationist policy in the seventeenth century

Because they already became a tributary state to China, they were invaded by Japan and eventually were conquered by the Manchus. They felt like "a shrimp among two whales", or in other words, inferior to the Japanese and Chinese, so they started their own country and excluded all foreigners except very few selected Japanese and Chinese.

Where’s the paragraph? ?

Ialways thought that he thought it wasn’t fair because he thinks that people should be able to experience things and think outside of the box, or see color and add brightness and happiness to their lives but idk.