Tolui

Although he never held the imperial title, Tolui (c. 1191-1232) became the forefather of more reigning monarchs than any of his brothers: from his sons descended the great khans Möngke and Kublai, the Yuan emperors of China, and the Ilkhans of Persia. He was the youngest son of Genghis Khan and Börte, and by the steppe custom that made the youngest son keeper of the hearth, he inherited his father's home territories in Mongolia along with the largest share of the Mongol army.

Tolui's reputation rested on his generalship. He served through the war against the Jin dynasty in north China and held major commands in the conquest of the Khwarazmian Empire, where he directed the campaigns in Khurasan that destroyed the cities of Merv and Nishapur — operations remembered in the Persian chronicles for their exceptional destructiveness. After Genghis Khan's death in 1227, Tolui administered the empire as regent for two years until a kurultai confirmed his brother Ögedei as great khan in 1229, in accordance with their father's wishes. He then campaigned again in north China, sharing command in the final offensives against the Jin.

He died in 1232, during that war. The Secret History of the Mongols relates that when Ögedei fell gravely ill, Tolui offered himself to the spirits in his brother's place, drinking a ritual draught and sickening soon after — an account whose literal accuracy cannot be established, but which reflects the devotion later tradition ascribed to him. He was about forty years old.

Tolui's marriage proved as consequential as his campaigns. His chief wife, Sorghaghtani Beki, was a Kereit princess and niece of the ruler Toghrul, and a Christian of the Church of the East. Widowed, she declined remarriage and devoted herself to the careers of her four sons: Möngke, Kublai, Hulagu, and Ariq Böke. Her statecraft helped engineer the transfer of the great khanate from Ögedei's line to Möngke in 1251, the so-called Toluid revolution. Thereafter the family's branches divided the Chinggisid world among themselves: Kublai founded the Yuan dynasty in China, Hulagu the Ilkhanate in Persia, while the Golden Horde of Jochi's heirs and the Chagatai Khanate in Central Asia continued under the other branches of Genghis Khan's line. Tolui was posthumously honored by the Yuan court with an imperial temple name, an emperor in retrospect though never in life.