Genghis Khan died in August 1227 during a military campaign against the Western Xia kingdom. The exact cause of his death remains uncertain and has been the subject of several theories. The most credible historical sources suggest that he fell ill with a fever and died within about eight days, possibly from a disease such as the bubonic plague, typhus, or another infectious illness. Other less substantiated accounts include death from battle injuries (such as a fall from a horse or an arrow wound), or an assassination involving a Tangut princess. However, these latter stories are considered likely later legends or misinformation spread to protect the empire's stability at the time. After his death, his passing was kept a secret for strategic reasons during the ongoing campaign. His burial site remains unknown but is said to be near the sacred Burkhan Khaldun mountain in Mongolia.