1. river-valley civilizations developed in sumer, egypt, china, and the indus river valley. 2. after you have completed your outline, use the outline to write a 3-paragraph essay comparing two of the river valley civilizations: mesopotamia, egypt, the indus river valley, and the yellow river valley/china. 3. the first paragraph should be your introduction. the second paragraph should be a paragraph about the similarities between the two civilization. finally, the third paragraph should be a paragraph describing the differences between the two civilizations.