10,000 Pharaohs?

From this story (Rampage before dawn ignites protest chaos) in The Scotsman on the rabble riots in Edinburgh, can someone explain this:

"In the Springkerse area of Stirling, protesters pulled the protective iron grill from the windows of a Burger King restaurant and smashed its windows. The wall was dubbed in graffiti: "10,000 Pharaohs Six Billion Slaves.""

Where does the magic figure of 10,000 come from?