China is surrounded by deserts and mountains. These acted natural barriers, separating China from the rest of the world. But not all China's geography were barriers. China has two major river systems that provided fertile soil and safe drinking water.
The early people called the rivers in China "The Great Sorrow". That's because each spring the rivers would overflow their banks.
The Yangtze River had high banks which kept the homes built on high ground safe. But not all homes were built on high ground.
The other major river system, the Huang He (the Yellow River), has low banks. Some early people built homes on stilts, to try and keep their homes safe during the flooding season. It was not until the early engineers of ancient China learned the techniques of flood control that the homes along the Yellow River survived more than one season.