The earliest civilizations developed in fertile river valleys, where the conditions were right to support large, settled populations. This book tracks how social hierarchies, religion, culture, written language, technology, and more developed first in Mesopotamia and then independently in the Nile, Indus, and Yellow River Valleys. A timeline helps readers get a better grasp of what developments were happening simultaneously in different parts of the world. This title will give readers a real appreciation for the contributions of each of these influential civilizations.