Earliest signs of complexity and statehood in mesopotamia (southern iraq): writing, urbanization, agriculture. Environmental context: low rainfall: water comes mainly from tigris and euphrates, dramatic spring floods: silt (chokes canals, plain is flat & poorly drained: salinization (salt build-up) Tigris and euphrates river systems: flow from eastern turkey through syria, iraq, and empty into the persian gulf, not conducive to agriculture in themselves; they are not entrenched into the landscape, and tend to meander over time (shifted) Silt deposited as rivers lose velocity and empty out into the persian gulf; the. Persian gulf are therefore a lot farther south than it was 5000 years ago: most fertile soil found on alluvial floodplains. Problem: most of southern iraq is desert, and water tends to dissipate quickly. Complex irrigation systems were built, but in this hot, dry environment, the water evaporated and left behind salt, which accumulated in the soil (salinization) Types of plant domesticates: wheat, barley, lentils, peas.