In third and fourth place respectively are Andrew Carnegie and John D Rockefeller, whose names still adorn upstanding civic institutions across the US. Cornelius Vanderbilt is at 10 and John Jacob Astor at 14.
The slot below the mysterious Mansa Musa is a whole family. This, of course, would be the Rothschild clan.
"The Rothschild family are the richest people on earth today with assets that total at least US$350 billion," the site claims. "Their net worth is difficult to peg because their holdings are so vast but without question they are the most powerful family in the world."
Top 10 most wealthy (US$)
1. Mansa Musa I $400b
(Ruler of Malian Empire, 1280-1331)
2. Rothschild Family$350b
(banking dynasty, 1740-today)
3. John D Rockefeller$340b
(industrialist, 1839-1937)
4. Andrew Carnegie $310b
(industrialist, 1835-1919)
5. Tsar Nicholas II of Russia $300b
(last Emperor of Russia, 1868-1918)
6. Osman Ali Khan, Asaf Jah VII $236b
(last ruler of Hyderabad, 1886-1967)
7. William the Conqueror $229.5b
(King of England, 1028-1087)
8. Muammar Gaddafi $200b
(former Libyan leader, 1942-2011)
9. Henry Ford $199b
(Ford Motor Company founder, 1863-1947)
10. Cornelius Vanderbilt $185b
(industrialist, 1794-1877)
- Independent