Simplify the following text for a Grade 7 native English-speaking person.
Original: While China ultimately did not sign the Simla Convention , a similar treaty , the tripartite Treaty of Kyakhta , was signed by Mongolia , the Republic of China and Russia on 25 May 1915 .
Simplified: Instead , a very similar treaty was signed by Mongolia , China , and Russia on 25 May , 1915 . This treaty was called the tripartite Treaty of Kyakhta .