I would be interested to know what sources did you come across?
Jack Weatherford is the New York Times bestselling author of Genghis Khan and the Making of the Modern World, which sold over 300,000 copies
In 2006 he spoke at the United Nations to honor the 800th anniversary of the founding of the Mongol nation by Genghis Khan. In 2007 President Enkhbayar of Mongolia awarded him Mongolia's highest honor for military or civilian service.
His grave, as far as I've read, isn't hidden. It is kept from public knowledge because the Mongols see it as a sacred place. But the general location of his burial is known: Burkhan Khaldun near the Onon River.