[Redbob]

"Today's Saudi ideology has its roots in the 1700s, when a desert preacher, Mohammed bin Abd al-Wahhab, began to condemn the Islam then practiced in central Arabia as decadent and dominated by superstitious veneration of shrines, dubious holy men and even trees.

The puritanical preacher's followers, allied with the powerful Saud family, then destroyed many shrines in Mecca and Medina, including some over the supposed graves of companions of Muhammad. Outrage over these acts in the wider Muslim world contributed to a military defeat of the initial alliance between the Saudis and the sheik in 1818 by Egyptian and Turkish forces. Pious and wealthy families rebuilt many shrines."
- Hugh Pope, WSJ, 8-18-4

[Redbob]

"Some 26 years ago, Saudi Arabia ratified a United Nations convention committing itself to safeguarding properties of outstanding cultural value. But so far, the Saudis haven't nominated anything in the kingdom to join the 611 cultural-heritage sites in the world that are registered with the U.N."

Well, there's a simple explanation for THAT.