Last night when Brian came home I told him what they had been doing. He said "so they've been playing that they're in the Fertile Cresant?" I told him that I didn't think so, that they were just having fun building houses. Which Micah overheard and instantly corrected me! He explained that they were building houses in the Fertile Cresant, and even showed us where the Tigris river was and where the Euphrates river was!
And now their house are homes to lizards, toads, and lizard eggs, along with all the little play animals :)