Why were there so many poor people in the Tang Dynasty?

There are many poor people. Any system will also face polarization between the rich and the poor. We can only try to narrow the gap or improve the level of security, but we cannot eliminate the gap between the rich and the poor. Because under any system, there will be no absolute fairness, and most of the resources will be in the hands of those in power. Of course, on the other hand, if all resources are in the hands of the poor, they will be wasted if they are not used well, and they will not be poor if they are used well, and they will become rich and treat the poor among the rich. Just like the boy who killed the dragon, he will gradually become a new dragon in the face of the wealth left by the dragon.