On this day, 65 years ago, May 31, 1960 (May 7, 1960, the lunar calendar), China and Mongolia signed a Treaty of Friendship and Mutual Assistance. On May 31, 1960, the China-Mongolia Treaty of Friendship and Mutual Assistance was signed in Ulaanbaatar. Effective on October 12 of the same year. The two parties stated that they respect each other's sovereignty and territorial integrity and do not interfere in each other. Consolidate and develop friendly and cooperative relations on the basis of internal affairs, equality and mutual benefit.