Really? So what do you know?
Not in 1972 but Chinese troops were in Vietnam during Vietnam war.
Chinese source states:
一千一百人阵亡,四千二百余人负伤。同时还详细披露了中国军队的战绩:中国防空部队在越南对空作战共二千一百五十三次,击落敌机一千七百零七架,击伤一千六百零八架;铁道部队则在越南新建铁路一百一十七公里,改建铁路三百六十三公里;同时入越的还有通信工程大队、后勤部队、筑路部队、扫雷工作队、民兵等。中国给越南的物资援助,总额达二百亿美元
Chinese troops Vietnam War casualties: 1,100 killed, four thousand two hundred wounded. Also detailed disclosure of the Chinese army's record: Chinese air defense troops in Vietnam conducted a total of two thousand one hundred fifty- three times combat, one thousand seven hundred and seven enemy aircraft shot down, one thousand six hundred and eight wounded; Railway troops in Vietnam built one hundred and seventeen kilometers of railway, reconstructed three hundred sixty-three km railway; while the more there are communications engineering battalion, logistics units, roads construction troops, demining teams. China's assistance to Vietnamese totaling twenty billion US dollars back then.