They are not using brick stones, they are literally using wood. It's a city of wood. And we also know that there was a very strict social class system that developed in the Shang Dynasty. We know that the upper class lived within the city walls. You want to talk about walls? These guys had walls that were 118 feet wide of just packed earth. It's thought that these 1.2 square miles of walls took about 10,000 men 12 years to build.