There is no hard evidence that any of those things happened. It may well be that they are after-the-fact embellishments designed to explain a remarkable circumstance of history: the location of Genghis' tomb remains a mystery.
The Mongol Empire receded almost as fast as it spread -- a fact that may have played a big role in keeping Genghis' final resting place a secret. For centuries, the people of Mongolia retained a traditional, nomadic lifestyle that left little time to contemplate the distant past. In the 20th century, the Soviet Union dominated Mongolia and, while it modernized the country, it feared Mongolian nationalism, and so discouraged any deep look into the nation's history.
But the last 20 years have seen a burst of interest in Genghis Khan. Abroad, his reputation as a bloodthirsty barbarian has undergone a substantial revision, thanks in part to books like the bestselling Genghis Khan and the Making of the Modern World. Meanwhile, a new, high-budget museum exhibition is touring the United States that emphasizes some innovations developed by Genghis Khan, including intercontinental commerce, religious pluralism and meritocracy.
In Mongolia, Ghengis is revered to a degree approaching that of a deity. His image appears everywhere, including on a tapestry in Ulaanbaatar's main monastery, as well as a statue in front of the parliament building. Ulaanbaatar's airport and popular brands of beer and vodka are named after him.
Given the revival of his legacy, it's not surprising that there has been an awakening of interest in finding his grave.
Since the collapse of Communism in 1991, two high-profile attempts have been mounted to find the grave. Both became mired in controversy.
The first was in the early 1990s, when the Japanese newspaper Yomiuri Shimbun sponsored an expedition that lasted four years and found the site of an early Mongol capital city, Avraga, and an intriguing circular structure three kilometers in circumference called the Almsgiver's Wall. But it found no sign of Genghis's tomb. The expedition did, however, engender suspicion among Mongolians, many of whom still believe the Japanese were in fact using Genghis as a pretext to secretly prospect for minerals.
Rumors also still circulate in Mongolia that the government, in an attempt to thwart the foreign expeditions, forbade the group from looking at Burkhan Kaldun, a mountain near the border with Russia where most scholars believe Genghis Khan is likely buried. It was on Burkhan Khaldun that, after his wife was kidnapped by rivals, Genghis prayed and received the revelation that he was to build an empire.
"Mongolians wouldn't accept them finding the grave, because of our beliefs," said D. Tumen, the chair of the archeology department at the National University of Mongolia. "This was the first time that an international expedition was undertaken, and Mongolians [were] afraid they would destroy or steal some things from the grave, so they didn't want them to be touched." Hard evidence of a government ban on exploration around Burkhan Khaldun has never surfaced, however.
The next major expedition was led by a retired commodities trader, Maury Kravitz, and a University of Chicago historian, John Woods. That expedition, too, did not look at Burkhan Kaldun, but at the Almsgiver's Wall. Even so, the group was forced to end its research early, in 2002, after a former prime minister of Mongolia visited and wrote a public letter alleging that the Americans had desecrated the site by driving cars over it, constructing temporary buildings too close to the wall, and storing human remains unceremoniously in pans.
Now there is a new group intent on finding the grave. It is called the Valley of the Khans project, and started work last year. It is led by Albert Yu-Min Lin, a materials science expert at the University of California-San Diego with no archeological background. The front page of the project's website  features a quote from the 2004 book Genghis Khan, by John Man, which hints at the expectations of the team:
"Surely, it is widely assumed, the grave of the ruler of half Eurasia would rival that of Tutankhamun. In fact, the search is not just for one grave but for a whole necropolis, a Mongolian Valley of the Kings, where Genghis's family and heirs ... must lie buried, along with wives, concubines, slaves, horses and Eternal Heaven knows what else of gold, jewelry, costumes and weapons the imagination can conjure up."
"If the grave exists and if it were ever found, it would create a revolution in archeology, scholarship, cash-flow and - since China claims Genghis as its own - international relations."
But the Valley of the Khans website doesn't quote the next lines of Man's book: "The discovery of the grave would signal the start of a feeding frenzy, attracting funds, most of them probably in dollars, to the delight of both the institutions that already exist and many more that would spring up overnight. Universities would rival tour companies for control of access, with the government acting as umpire, trying to seize a share of the inflow for the nation, and probably failing, given the current passion for privatization and the prevalence of bribery."
The potential for that sort of unseemly chaos around the resting place of Mongolia's greatest hero has created deep misgivings in Mongolia about the search, and so while researchers close in on their goal and the answer to one of archeology's great unanswered questions, another question is increasingly being asked in Mongolia: Should Genghis Khan's grave be found?
Editor's Note: Joshua Kucera is a Washington, DC,-based freelance writer who specializes in security issues in Central Asia, the Caucasus and the Middle East.