What natural feature formed part of the northern border of Shang China?

Yellow sea formed part of the northern border of Shang China.

Explanation:

Yellow sea is one of the most important natural feature of China and it is lying on the mainland China and on the peninsula of Korea. It has shallow water and it is one of the most important places in the world for the migratory birds to come.

Yellow sea is known well for fishing also. It is known as the yellow sea because the surface of the sea turns into a golden yellow colour because of the storm of the sand which comes from the Gobi desert.