Jamukha (Cyrillic: Жамуха) was a Mongol military and political leader and the chief rival to Temüjin (later Genghis Khan) in the unification of the Mongol tribes.
Jamukha born in the Jadaran, a sub-tribe of the Khamag Mongol confederation, and Jamukha was an anda (childhood friend) and a blood brother to Temüjin.
According to The Secret History of the Mongols, when Börte, wife of Temüjin, was abducted by the Three Mergids; Wang Khan, Jamukha and Temüjin combined forces against the Mergids to recover her.
In 1201, the thirteen remaining tribes (Mergid, Tatar, Naiman etc..) and Mongol tribes not allied with Temujin (Jadaran, Taichuud etc..) tribal leaders assembled a khurultai and elected Jamukha as Gur Khan, universal ruler, a title used by the rulers of the Kara-Khitan Khanate. Jamukha's assumption of this title was the final breach between Temüjin and Jamukha, leading Temüjin to form a coalition of tribes to oppose him. In the fall of that year, a great battle broke out between Jamukha's alliance and Khereit-Khamag Mongol alliance at the Ergune valley (Battle of the Thirteen sides). This decisive battle ended with Temujin's victory and eventual ascension as Khan of all united Mongol tribes.
Jamukha was less successful in coalition-building because, unlike Temüjin, he maintained traditional divisions between tribes in his forces and assigned commands by hereditary rank rather than merit. In particular, Jamukha did not recruit shepherds who lacked tribal status in the Mongol tradition. This allowed Temüjin to recover from a series of military defeats inflicted by Jamukha and to emerge victorious.
Jamukha was eventually betrayed to Temüjin by his followers in 1206. Temüjin executed Jamukha's betrayers on the principle that betrayal merits the harshest punishment. The Secret History of the Mongols states that Temüjin offered renewal of their brotherhood, but Jamukha insisted that just as there was room for only one sun in the sky, there was room only for one Mongol lord. He asked to be executed by dying a noble death without the spilling of blood. His request was granted by having his back broken by Temüjin's soldiers.