Surqaghtani Beki, posthumously Empress Xianyi Zhuangsheng, was a Keraite princess and daughter-in-law of Genghis Khan. Married to Tolui, Genghis' youngest son, Sorghaghtani became one of the most powerful and competent people in the Mongol Empire. She made policy decisions at a pivotal moment that led to the transition of the Mongol Empire towards a more cosmopolitan and sophisticated style of administration. She raised her sons to be leaders and maneuvered the family politics so that all four of her sons, Möngke Khan, Hulagu Khan, Ariq Böke, and Kublai Khan, went on to inherit the legacy of their grandfather.