Why do Korean names sound so similar to those in China?

Korean archives and school records are all Chinese names. They had Chinese names when they were young. Traditional Chinese can be used in Korea, which is basically known to all.

For a long time, Chinese was the official language of the ancient Korean dynasty, and later generations invented their own characters. After 1950s, due to the rise of nationalism, Chinese characters were abolished in North Korea and South Korea. But although Chinese is no longer used, Chinese characters still account for 70% of Korean/Korean. The so-called Chinese characters are simply transliteration of the word in Korean (the so-called Korean characters are actually square characters piled up by pinyin, as long as you know the phonetic symbols, even if you don't know what it means at all). Most Korean names are written in Chinese characters, which is not difficult to translate. However, because there are many homophones in Chinese, one Korean character may correspond to several Chinese characters, which is easy to be confused. So Koreans will attach their Chinese names to the Korean names on their ID cards. However, China people often make mistakes when translating Korean names, because they often don't know China's name on their identity cards when translating.