Chichen Itza was built in the year 525 a.C. It is not possible to explain the dissapearance of the Mayan civilization. While the northern Maya country thrived until the arrival of the Spanish to the Americans, the southern empire was already gone.

The death of Genghis Khan is shrouded in mystery. Legends say he was buried in an unmarked grave, and that anyone who knew the location of his grave was killed to keep it a secret.