Question: Yelü Chucai was a retainer of which founder of the Mongol Empire?
Sentence (from "Yelü Chucai"): He was the first of Genghis Khan's retainers to formulate policy during the Mongol conquests, and he also introduced many administrative reforms in North China during the reign of Genghis Khan and his successor Ögedei.
Relevant evidence: Yes