on 1912 november 3, russia signed a deal 《俄蒙协约》with mongolia to mine in mongolia in exchange for saying mongolia is autonomous. china was not happy. so in 1913 september 18, sun baoqi () signed a new agreement between china and russia《中俄声明文件》. china agrees not to put troops in mongolia and recognize the russian-mongol deal 《俄蒙协约》. in return, russia recognizes that china has suzerainty over mongolia. so china's power over mongolia changed from sovereignty to suzerainty.