Can Mongolians understand what Koreans say?

God, they are not related by blood, let alone brothers.

Mongolians who can't speak Korean can't understand Korean.

Mongolians who can speak Korean can understand Korean,

It's that simple.

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It is true that Mongolia is descended from Donghu people. But the Korean nationality is a branch of Huaxia-Han nationality, not a descendant of Donghu people. In ancient times, Koreans always said that they were descendants of Ji Zi, and Ji Zi was a minister of Shang Dynasty, which had nothing to do with Mongolian Donghu. Moreover, during the Qin Dynasty, a large number of China people could not bear the abuse of Qin Shihuang and fled to the Korean peninsula collectively. This is what the Koreans themselves said. During the Ming Dynasty, many Koreans immigrated to the north of China. Many people in North Korea now record that their ancestors came from somewhere in China during the Ming Dynasty. Others don't say that the newly elected Secretary-General of the United Nations was either an ancestor or a China native in the Ming Dynasty.

These things are recorded in many ancient materials.

You can refer to Shangshu, Chunqiu, Historical Records, Hanshu and Sinology written by China people.

And the History of the Three Kingdoms, History of Korea, History of National Dynasties, History of Li Chao and so on written by Koreans.

I have electronic versions of these books, and the landlord can ask me for them if he wants to read them.