Whether a river is fertile or not depends largely upon the quality of the soils it flows through. If the soils are productive, the water will be teeming with fish, and local tribes can rely on it for their staple food.
In places where rich rivers regularly flood, such as the Amazon, the wealth of the river is transferred to the land.If the soils are poor, the river will provide little and the natives must go into the forest to look for food.
