Only from the middle of the 1st millennium BC. the process of expanding the territory occupied by the ancient Chinese begins. They gradually spread southward, first to the Yangtze Basin, and then further south. On the verge of our era, the ancient Chinese state went far beyond the Yellow He basin, although the northern border of the ethnic territory of the ancient Chinese remained almost unchanged.
Crossing the loess plateau from north to south, lying at a level of 400-1500 m, the Yellow River turns east, flows along the Central China Plain and flows into the Bohai Bay. The channel of the Yellow River in its lower reaches has repeatedly shifted over the past millennia; the configuration of the coastline of the Bohai Bay, which is continuously receding under the influence of river sediments, also changed.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.