Painted on these grounds is a black & white checkered motif covered with idols  similar to the ones you carry. A large being approaches...  Og speaks: "Queen to queens  level 3."  Which piece do you want to move? 
I always thought that "large being" description of Og was rather strange, but upon researching the name, it seems he might have been based on the biblical Og, who was a giant. 

Caryatid Guards are most likely named after these things, although the ones in the game look like ordinary knights in armor, not female figures.