Tolui was the third son of Genghis Khan, the founder of the Mongol Empire. He played a significant role in the expansion of the empire during the early 13th century. Tolui was known for his military leadership and was involved in several key campaigns, including the conquest of Western Xia and Jin Dynasty territories. After Genghis Khan's death in 1227, Tolui became the regent of the Mongol Empire while his brother, Ogedei Khan, was elected as the Great Khan. Tolui's leadership helped solidify the empire's power, and he is often recognized for his contributions to the Mongol military strategies and governance.