They had these standard bricks and this brick size and many of these symbols that they used were found throughout these sites. We said, we don't know whether they were controlled by one ruler or one emperor, but there was definitely a lot of cultural interchange to the point that they were using the same size bricks, they were using the same symbols, they were using the same units of measurement. And also, as you can imagine, having a unit of measurement that precise, that small, implies that they were great builders. And the evidence we find today says yes, they were. This is a picture of the site at Mohenjo-Daro in modern-day Sindh, Pakistan. And you can see how tight this brickwork is. Even by modern standards, this is quite good.