In the Old World, settled life developed on the higher ground from Iran to Anatolia and the Levant and in China in the semiarid loess plains and the humid Yangtze valley. In contrast, the earliest civilizations based on complex and productive agriculture developed on the alluviums of the Tigris, Euphrates, and Nile rivers. Villages and townships existed in the Euphrates valley in the latter part of the 7th millennium bp. Soon the population was dispersed in hamlets and villages over the available area. Larger settlements provided additional services that the hamlets themselves could not. Sumer, located in the southernmost part ...(100 of 27369 words)