Has done what if it’s a question make it clear for us to answer
https://study.com/academy/lesson/how-geography-isolated-ancient-china.html
That video will explain everything. I have already learned this in school, and it is very important on the test. VERY IMPORTANT.
The main reason for the wall's construction had always been defense. Since China's first dynasty, the empire faced a near-constant threat of attack from the nomadic tribes to the north. This included those famed Mongols as well as lesser-known groups like the Xiongnu and the Göktürks.
Well there's is frozen sea weed and there is plankton and hair grass