What feature do the arkansas river valley and the mississippi alluvial plain region have in common

Both these rivers formed layers of high nutrients soil around them.

Due to high nutrient and large amount of water reserves, it is really easy of plants to obtain all of their needs in order to grow.

Because of this, the area near these rivers were really perfect for civilization to grow. The crops grow rapidly in this area, providing the people with enough food and water supply for them to sell and consume for themselves.