When Genghis Khan dropped down on the cities of Khwarizm, he commanded an army of about 100,000 to 125,000 horsemen, supplemented by Uighur and other Turkic allies, a corps of Chinese doctors, and engineers for a total of 150,000 to 200,000 men. By comparison, the Khwarizm ruler had some 400,000 men under arms across his empire, and they were fighting with the home advantage on their own territory.
The Mongols promised justice to those who surrendered, but they swore destruction to those who resisted. If the people accepted and acted as relatives should by reciprocating the offer of kinship by offering food, then the Mongols would treat them as family members with a guarantee of protection and certain basic familial rights; if they refused, they would be treated as enemies. Genghis Khan’s offer to the besieged was as simple as it was horrifying, as when he sent this message to the citizens of Nishapur: “Commanders, elders, and commonality, know that God has given me the empire of the earth from the east to the west, whoever submits shall be spared, but those who resist, they shall be destroyed with their wives, children, and dependents.” The same sentiment found expression in many documents of the era, one of the clearest in the Armenian chronicle that quotes Genghis Khan as saying that “it is the will of God that we take the earth and maintain order” to impose Mongol law and taxes, and to those who refused them, the Mongols were obligated to “slay them and destroy their place, so that the others who hear and see should fear and not act the same.”
Some cities surrendered without fighting. Others fought for a few days or weeks, and only the hardiest of defenders held out for more than a few months. Genghis Khan had learned much from his campaigns against the Jurched cities: not only how to capture heavily fortified cities, but how to treat them afterward, in particular how to most efficiently plunder them. He did not want to repeat the mistakes of the chaotic plunder of Zhongdu. In Khwarizm, he introduced the new and more efficient system of first emptying the city of all people and animals before beginning to loot, thereby minimizing the danger to his men as they plundered.
Before the plundering began, the Mongol warriors followed a similar procedure toward the enemy population in each hostile city. First, they killed the soldiers. The Mongols, dependent on cavalry, had little use for an infantry trained to defend fortress walls, and, more important, they did not want to leave a large army of former enemies blocking the route between them and their homeland in Mongolia. They always wanted a clear, open way home. After executing the soldiers, the Mongol officers sent clerks to divide the civilian population by profession. Professional people included anyone who could read and write in any language—clerks, doctors, astronomers, judges, soothsayers, engineers, teachers, imams, rabbis, or priests. The Mongols particularly needed merchants, cameleers, and people who spoke multiple languages, as well as craftsmen. These workers would be put to use by the Mongols, who themselves practiced no crafts other than war, herding, and hunting. Their growing empire needed skilled workers in almost every service imaginable, including smiths, potters, carpenters, furniture makers, weavers, leather workers, dyers, miners, papermakers, glassblowers, tailors, jewelers, musicians, barbers, singers, entertainers, apothecaries, and cooks.
People without occupations were collected to help in the attack on the next city by carrying loads, digging fortifications, serving as human shields, being pushed into moats as fill, or otherwise giving their lives in the Mongol war effort. Those who did not qualify even for these tasks, the Mongol warriors slaughtered and left behind.
In Genghis Khan’s conquest of central Asia, one group suffered the worst fate of those captured. The Mongol captors slaughtered the rich and powerful. Under the chivalrous rules of warfare as practiced in Europe and the Middle East during the Crusades, enemy aristocrats displayed superficial, and often pompous, respect for one another while freely slaughtering common soldiers. Rather than kill their aristocratic enemy on the battlefield, they preferred to capture him as a hostage whom they could ransom back to his family or country. The Mongols did not share this code. To the contrary, they sought to kill all the aristocrats as quickly as possible in order to prevent future wars against them, and Genghis Khan never accepted enemy aristocrats into his army and rarely into his service in any capacity.
Genghis Khan had not always pursued this policy. In the first conquests of the cities of the Jurched, the Tangut, and the the Black Khitan, Genghis Khan had often protected the rich and even allowed rulers to stay in office after he defeated them. But the Jurched and the Tangut had betrayed him as soon as his army withdrew. By the time Genghis Khan arrived in the Muslim countries of central Asia, he had learned his lesson about the loyalty, dependability, and usefulness of the rich and powerful. In his keen awareness of public attitudes and opinions, he also recognized that the common people cared little about what befell the idle rich.
By killing the aristocrats, the Mongols essentially decapitated the social system of their enemies and minimized future resistance. Some of the cities never recovered enough to rebuild after the loss of aristocrats on the battlefield or from the annihilation of their families. Genghis Khan wanted officeholders who were loyal and indebted to the Mongols alone for their positions of power and prestige, and for this reason he recognized no titles other than those granted by him. Even an allied prince or king who wished to retain an older title had to have it reconferred on him by the Mongol authorities. In his report on his trip to Mongolia from 1245 to 1247, the papal envoy Giovanni Di Plano Carpini complained frequently about the lack of respect that Mongols showed the aristocratic people. The lowest-ranking Mongol could walk in front of visiting kings and queens and speak rudely to them.
The fate of the sultan’s mother, who had been the most powerful woman in the empire, showed the Mongol attitude toward aristocratic women. They captured her and killed most members of her court and some two dozen members of her family. Then they sent her off to live the remaining decade of her life in ignominious servitude in Mongolia, where she disappeared from history. Such a woman earned no prestige or consideration by virtue of her birth; she, like a captured man, was only as good as her skills, work, and service.
When the Mongols passed through a city, they left little of value behind them. In a letter written just after the invasion, the geographer Yaqut al-Hamawi, who barely escaped the Mongols, wrote glowingly of the beautiful and luxurious palaces that the Mongols had “effaced from off the earth as lines of writing are effaced from paper, and those abodes became a dwelling for the owl and the raven; in those places the screech-owls answer each other’s cries, and in those halls the winds moan.”
Genghis Khan epitomized ruthlessness in the eyes of the Muslims. Chroniclers of the era attribute to Genghis Khan the highly unlikely statement that “the greatest joy a man can know is to conquer his enemies and drive them before him. To ride their horses and take away their possessions. To see the faces of those who were dear to them bedewed with tears, and to clasp their wives and daughters in his arms.” Rather than finding such apocalyptic descriptions derogatory, Genghis Khan seemed to have encouraged them. With his penchant for finding a use for everything he encountered, he devised a powerful way to exploit the high literacy rate of the Muslim people, and turned his unsuspecting enemies into a potent weapon for shaping public opinion. Terror, he realized, was best spread not by the acts of warriors, but by the pens of scribes and scholars. In an era before newspapers, the letters of the intelligentsia played a primary role in shaping public opinion, and in the conquest of central Asia, they played their role quite well on Genghis Khan’s behalf. The Mongols operated a virtual propaganda machine that consistently inflated the number of people killed in battle and spread fear wherever its words carried.