Describe the roles of geography and the environment on the development of early river valley civilizations

(give specific examples from at least three different river valley civilizations)

Civilizations have always tended to develop in regions with specific geographic features. The River Valley Civilizations developed around major river systems. The civilizations sprung up around the Tigris and Euphrates Rivers. The rivers provided water for domestic use and agriculture. The flooding of these rivers provide fertile soils for the development of agriculture. Harrapa and Mohenjo-daro flourished because the flooding of the rivers provided fertile soils for agriculture and this facilitated the development of permanent settlements and to the development of these civilizations. 

it is B compares two rocks or layers.