Family relationships among the figures in this history are both fundamental to Mongol culture and subject to change surprisingly quickly. The nature of kinship in medieval Mongol society, as described by Weatherford, is nothing like our modern conception of it. Family relationships could be entered into willingly (as in a bond of blood brotherhood, taken by Jamuka and Temujin and by Ong Khan and Yesugei), or one could be born into them. However, neither arrangement is permanent: Temujin kills his half-brother Begter and his blood-brother Jamuka.

On a larger scale, relationships between Mongol clans before the rise of Temujin were similar to relationships between members of an extended family. This was often accurate in a literal sense, as many of the clans indeed descended from a common ancestor, but we see in the course of Weatherford’s history that these relationships could also be more of an “idiom” than a literal status. For example, when Temujin conquered a nearby clan, he would ritually adopt its members into his own. There was nothing symbolic about this adoption; the new clan members were treated just as blood relatives would be.

Yet even when kinship bonds were well-established, they were still mutable. A quarrel between relatives or blood brothers could be set off by a single insult and the resulting feud could last for generations.