History
Genghis Khan's Strategies to Unify the Mongol Tribes
Quick fact
Genghis Khan broke the power of traditional tribal aristocracy by appointing followers based on merit, not lineage, and created a personal guard (Kheshig) that was both a military unit and a tool to ensure loyalty.
Why this is interesting
How did a single leader unite dozens of feuding nomadic tribes into a force that would conquer the largest contiguous empire in history?