The researchers studied how different elements, like the economy, resources, population, and technology, move between cities in China's urban areas. They looked at 18 city clusters and found that Guangdong-Hong Kong-Macao had the most internal flows, while Shandong Peninsula had the tightest connections within its cities. They also discovered that capital cities and important cities had a big impact in these networks. The researchers say this study can help guide the development of urban areas to be more coordinated and sustainable.