How did Genghis Khan unite the Mongol tribes?

Genghis Khan united the Mongol tribes by systematically dismantling the traditional clan and tribal systems that had historically caused fragmentation. His approach was characterized by both strategic alliances and ruthless military force.123

To consolidate power, he followed a policy of eliminating rival aristocrats and clan leaders who could serve as centers of resistance. When he defeated enemy tribes—such as the Tatars, Merkit, and Kereit—he often dispersed the common people among his own forces, effectively turning them into loyal soldiers and servants. By doing so, he replaced the existing tribal structure with a new, unified nation organized for war.12

His military was restructured using a decimal system, ensuring rigid discipline and absolute loyalty to him and his selected commanders. This process culminated in 1206, when an assembly of leaders at the River Onon proclaimed him chinggis khān (universal emperor) of the Mongolian steppe. This unification transformed the Mongols from a collection of warring tribes into a powerful, cohesive force capable of large-scale conquest.231