▁diplom atic ▁relations ▁with ▁Mong olia ▁on ▁October ▁ 1 6 , ▁ 1 9 4 9 ▁and ▁both ▁nations ▁signed ▁a ▁border ▁treat y ▁in ▁ 1 9 6 2 . ▁With ▁the ▁S ino - S ov iet ▁split , ▁Mong olia ▁aligned ▁itself ▁with ▁the ▁Soviet ▁Union ▁and ▁asked ▁for ▁the ▁deployment ▁of ▁Soviet ▁forces , ▁leading ▁to ▁security ▁concerns ▁in ▁China . ▁As ▁a ▁result , ▁bil ater al ▁t ies ▁remained ▁t ense ▁until ▁ 1 9 8 4 , ▁when ▁a ▁high - level ▁Chinese ▁deleg ation ▁visited ▁Mong olia ▁and ▁both ▁nations ▁began ▁to ▁survey ▁and ▁dem arc ate ▁their ▁borders . ▁In ▁ 1 9 8 6 , ▁a ▁series ▁of ▁agre ements ▁to ▁bol ster ▁trade ▁and ▁establish ▁transport ▁and ▁air ▁links ▁was ▁signed . ▁In ▁ 1 9 8 8 , ▁both ▁nations ▁signed ▁a ▁treat y ▁on ▁border ▁control . ▁Mong olia ▁also ▁began ▁as ser ting ▁a ▁more ▁independent ▁policy ▁and ▁purs ued ▁more ▁friendly ▁t ies ▁with ▁China . ▁Mong olia ▁has ▁always ▁been ▁susp icious ▁that ▁China ▁wants ▁to ▁claim ▁Mong ol ian ▁territory , ▁and ▁concerned ▁by ▁fear s ▁of ▁China ' s ▁over pop ulation ▁pour ing ▁into ▁Mong ol ian ▁territory . ▁ ▁Modern ▁period ▁▁ ▁In ▁the ▁Post - C old ▁War ▁era , ▁China ▁has ▁taken ▁major ▁steps ▁to ▁normal ize ▁its ▁relationship ▁with ▁Mong olia , ▁emphas izing ▁its ▁respect ▁for ▁Mong olia ' s ▁so vere ig nt y ▁and ▁independence .