In traditional steppe systems of thought, everyone outside the kinship network was an enemy and would always be an enemy unless somehow brought into the family through ties of adoption or marriage. Temujin [later Genghis Khan] sought an end to the constant fighting between such groups, and he wanted to deal with the Tatars the same way that he had dealt with the Jurkin and the Tayichiud clans–kill the leaders and absorb the survivors and all their goods and animals into his tribe. Although this policy had worked with clans of hundreds, however, the Tatars were a tribe of thousands. For such a massive social transformation, he needed the full support of his followers, and to achieve that support he summoned a khuriltai [= loya jirga] of his victorious warriors.
The members of the khuriltai agreed to the plan, determining to kill Tatar males taller than the linchpin holding the wheels on a cart, which was not only a measure of adulthood but a symbolic designation of the nation itself, in much the same way that maritime people often use the ship as a symbol of their state. Once again, as a counter to the killing, Temujin wanted the surviving Tatars taken in as full members of his tribe, not as slaves. To stress this, he not only adopted another Tatar child for his mother, but also encouraged intermarriage. Until this time he had only one official wife, Borte, who bore him four sons and an unknown number of daughters, but he now took the aristocratic Tatar Yesugen and her elder sister Yesui as additional wives. The Tatars had had a much greater reputation than the Mongols, and after this battle, the Mongols took in so many Tatars, many of whom rose to high office and great prominence in the Mongol Empire, that the name Tatar became synonymous with, and in many cases better known, than the name Mongol, leading to much historic confusion through the centuries.
Intermarriage and adoption would not suffice, however, to achieve Temujin’s goal of merging the two large groups into one people. If kin groups were allowed to remain essentially intact, the larger group would eventually fragment. In 1203, therefore, the year after the Tatar conquest, Temujin ordered yet another, and even more radical, reformation of the Mongol army and tribe.
He organized his warriors into squads, or arban, of ten who were to be brothers to one another. No matter what their kin group or tribal origin, they were ordered to live and fight together as loyally as brothers; in the ultimate affirmation of kinship, no one of them could ever leave the other behind in battle as a captive. Like any family of brothers in which the eldest had total control, the eldest man took the leadership position in the Mongol arban, but the men could also decide to chose another to hold this position.
Ten of the squads formed a company, or zagun, of one hundred men, one of whom they selected as their leader. And just as extended families united to form lineages, ten Mongol companies formed a battalion, or mingan, of one thousand men. Ten mingan were then organized into a tumen, an army of ten thousand; the leader of each tumen was chosen by Temujin, who knew the qualities needed in such a leadership position. He allowed fathers and sons and brothers and cousins to stay together when practical, but by forcing them into new units that no man could desert or change, under penalty of death, he broke the power of the old-system lineages, clans, tribes, and ethnic identities. At the time of his reorganization, he reportedly had ninety-five mingan, units of a thousand, but since some of the units were not staffed to capacity, the total number of troops may have been as low as eighty thousand.
The entire Mongol tribe became integrated by means of the army. Under this new system, all members of the tribe–regardless of age or gender–had to perform a certain amount of public service. If they could not serve in the military, they were obliged to give the equivalent of one day of work per week for public projects and service to the khan. This included caring for the warriors’ herds, gathering dung for fuel, cooking, making felt, repairing weapons, or even singing and entertaining the troops. In the new organization, all people belonged to the same bone. Temujin the boy, who had faced repeated rejections ascribed to his lower-status birth, had now abolished the distinction between black bone [distant relatives] and white bone [near relatives]. All of his followers were now one united people.
Historical speculation abounds as to how Temujin adopted the decimal organization of his people. Some of the earlier Turkic tribes used a similar military organization based on units of ten, and Temujin may well have borrowed it from them. Temujin, however, not only utilized the system as a military tactic for war, but he also employed it as the permanent structure for the whole society.