From August 1950, the communist 6th Cavalry Division, 7th Infantry Division, and troops from communist Pingliang and Qingyang Military Sub-Districts totaling more than 15,000 begun their operation against the more than a dozen bands of bandits headed by chieftains including Guo Shuanzi (郭栓子), Ma Yanbiao (马彦彪), Ma Guoyuan (马国援) and others in Xiji (西吉), Longde (隆德), Helan Shan and Hexi Corridor regions.