Genghis Khan
© The Art Science Museum
Genghis Khan may have died of bubonic plague, and not from blood loss after being castrated or other causes bandied about over the centuries, a new study finds.

Genghis Khan, born Temüjin of the Borjigin clan in 1162, was one of the most famous conquerors in history. In 1206, he founded and served as the first ruler of the Mongol Empire, which, at the time of his death in 1227, was 2.5 times larger by territory than the Roman Empire, the new study's authors noted. His legacy has reached global dimensions: A study published in 2003 in The American Journal of Human Genetics suggested that about 1 in 200 men worldwide may be Genghis Khan's direct descendants.

While the conqueror's influence is well known, his death is shrouded in mystery. Genghis Khan's family and followers were instructed to keep his demise as their most hidden secret, since it happened during a vital stage of their war against the Western Xia, an empire the Mongols had fought for more than 20 years, the researchers said.

To honor or sully Genghis Khan's memory, both friends and foes of the Mongols told a number of legends about his death, the scientists said. One story claims he succumbed to blood loss after getting stabbed or castrated by a princess of the Tangut people, a Tibeto-Burman tribe in northwest China. Others suggested he died of injuries sustained after tumbling from his horse, fell in battle against the Chinese or died of an infected arrow wound during his final campaign against the Western Xia.

Genghis Khan
© DeAgostini/Getty Images
Genghis Khan is shown on his deathbed in this miniature from the Book of the Wonders of the World by Marco Polo and Rustichello, France.
In the new study, the researchers suggested that all of these legends were likely invented well after Genghis Khan's death.

"Deaths of the kings and emperors of greater China are often mixed with myth," study co-author Francesco Galassi, a physician and paleopathologist at Flinders University in Adelaide, Australia, told Live Science in an email. "Exciting, extraordinary causes of death are attributed to exceptional personages, when it is more reasonable to look for more common conditions, such as infectious diseases. In general, there is not sufficient evidence to support these legends."

For example, when Genghis Khan died, "he was still at the height of his powers, respected by his underlings and well cared for by his servants," study co-author Wenpeng You, a researcher of human biology at The University of Adelaide, told Live Science in an email. "This makes his death by political assassination or poisoning very unlikely."

While conducting medical research into the impact of disease worldwide, the scientists decided to focus on Genghis Khan's death. "The current COVID-19 pandemic prompted our thoughts towards consideration of ancient pandemics," Galassi said.

The researchers focused on "The History of Yuan," a historical text commissioned during China's Ming dynasty. That work stated that, from Aug. 18 to Aug. 25, 1227, during Genghis Khan's last campaign against the Western Xia, he felt unwell with a fever that ultimately killed him within eight days after the disease's onset. Prior research suggested he came down with typhoid fever, but Galassi and his colleagues noted that there was no mention of other typical symptoms of that disease, such as abdominal pain and vomiting.

The scientists diagnosed Genghis Khan not only by looking at his clinical signs, but also by using information about the diseases that Mongol troops and their enemies were suffering from at the time, as well as modern knowledge about the onset times of communicable diseases. They found that his symptoms matched those of the bubonic plague that was prevalent in that era, study co-author Maciej Henneberg, an archaeologist and paleopathologist at The University of Adelaide, told Live Science in an email.

The scientists acknowledged that such retrospective diagnostic research was inevitably limited by the lack of access to Genghis Khan's body; his burial site remains unknown. Still, "while we cannot be 100% certain about the exact cause of death due to these limitations, we can say that this clinical scenario is much more realistic and worthy of historical consideration than other way more far-fetched hypotheses," Galassi said.

All in all, the researchers suggested that Genghis Khan's fate may hold lessons for the present.

"The recent pandemic has once again shown that leaders of nations can contract infectious diseases, and despite their power, they cannot be shielded against naturally occurring phenomena such as infectious diseases," study co-author Elena Varotto, an anthropologist and bioarchaeologist at the University of Catania in Italy, told Live Science in an email. As such, Genghis Khan's death might serve as a "general example of the influence of diseases upon leadership, potentially capable of changing the course of history," she said.

The scientists detailed their findings online Jan. 11 in the International Journal of Infectious Diseases.