Genghis Khan's sons fought over the eldest son's birth before he named a successor, and his grave was never recorded

The Secret History of the Mongols records that before his war against the Khwarazm Shah, Genghis Khan's wife Yesui asked which of his four sons would rule if he died. He asked his eldest, Jochi, to speak. His second son, Chagatai, spoke first: "He was brought back from the Merkit. How can we let him rule?" Their mother had been captured by the Merkit before Jochi's birth. Jochi seized Chagatai by the collar and challenged him to archery and wrestling. The adviser Köke Če'üs rebuked Chagatai for shaming their mother. The two eldest then proposed the third son, Ögedei, and Genghis told them to rule separate domains. Genghis died in 1227 during the campaign against the Xi Xia. The Yuan History says he was buried at the Qinian valley; it gives no location. His youngest son, Tolui, held the regency in 1228, and in 1229 an assembly on the Kherlen River enthroned Ögedei "by the late emperor's will". Folklore says the escort killed everyone it met and that horses were ridden over the grave^†. UNESCO lists Burkhan Khaldun as his "reputed burial site". The area, once the closed Great Taboo zone, is now the Khan Khentii Strictly Protected Area, and the mountain has been off-limits to researchers since it became a World Heritage site.