Chingis Khan had 100,000 to 125,000 horsemen, with Uygur and Turkic allies, engineers and Chinese doctors -- a total of from 150,000 to 200,000 men. To show their submission, some offered food to the Mongols, and Chingis Khan's force guaranteed them protection. Some cities surrendered without fighting. In cities the Mongols were forced to conquer, after killing its fighting men, Chingis divided the survivors by profession. He drafted the few who were literate and anyone who could speak various languages. Those who had been the city's most rich and powerful he wasted no time in killing, remembering that the rulers he had left behind after conquering the Xi Xia and Ruzhen (Jin) had betrayed him soon after his army had withdrawn.