TIL More than one million Chinese soldiers crossed the Yalu River into North Korea during the Korean War. However, the Chinese were told to avoid any close connection with North Koreans and not to mingle or make friends

https://www.voanews.com/a/chinese-veterans-recall-korean-war/1709732.html

https://www.reddit.com/r/todayilearned/comments/152ium8/til_more_than_one_million_chinese_soldiers/