The relationship between the cultures of the Yellow River and the Yangtze River is they both relied heavily on agricultural production brought in from the rivers. Because of rapid population growth, both of these regions needed to create cities and states due to the large plethora of food. As well each region needed a form of a social organization, construction of dikes, and an irrigation system; these people also responded the same way to the dominance of their agriculture by becoming cultivators and joining the Chinese societies. However, others continued to hunt and gather, while some moved to hills, mountains or other places where there was less agricultural production. Furthermore, these regions also had trouble because the state of Chu attempted to control both of the valleys and also challenged the Shang dynasty for power.