 Ma Buqing had earlier fought against the Japanese, but because the Soviet threat was great, Chiang changed Ma's position, in July 1942, by instructing Ma to move 30,000 of his troops to the Tsaidam marsh in the Qaidam Basin of Qinghai.Chiang named Ma as Reclamation Commissioner, to threaten Sheng Shicai's southern flank in Xinjiang, which bordered Tsaidam.After Ma evacuated his positions in Gansu, Kuomintang troops from central China flooded the area, and infiltrated Soviet occupied Xinjiang, gradually reclaiming it and forcing Sheng Shicai to break with the Soviets.