Nanjing is the most embarrassing place to say that the whole ancient dynasty changed. The regime established here is not only very short-lived, but also almost destroyed by people. A good city like Nanjing is not only economically developed, but also has a large grain output and convenient transportation. Why is Nanjing not a good capital address of ancient dynasties?
This is actually related to the geographical location of Nanjing. Why is the geographical location of Nanjing awkward? We need to see the whole map of China. Nanjing is located in the North China Plain, with flat and open surroundings. It is the place where people gather the most, and because of the agricultural society, the most important thing is the production of grain, and Nanjing also has a very good planting environment, but this is also the reason why Nanjing is not easy to establish a capital city, which is very short-lived after its establishment.
Because you know that ancient city-states or fortresses were not built in a flat position around them, why is it because there is no good defense? You know, many fortresses even have their backs to mountains, and deep moats have been dug in front of them, but Nanjing is easy to attack and difficult to defend, so it is really difficult to be the capital, because once the enemy breaks through the border defense, it means that Ma Pingchuan has leveled the political center, which many kings do not want to see.
This is also the reason why people who choose to build their capital in Nanjing can't last long, because they are too rich, many people are jealous, and there is no good shelter around them, just like opening a sheepfold to let wolves come in and grab it. This is also the reason why later dynasties chose to build cities on the edge of North China Plain.