Irrigation

__**Why**__: Resulted in increased crop yields, population growth
 * Who**:
 * Mesopotamians
 * Made water flow from Euphrates to Tigris, using natural topology
 * Had issues like salt buildup in canals
 * Egyptians
 * Took water from the Nile during flood seasons
 * Highly successful, Nile very predictable
 * What**: Artificially diverting the natural flow of water to distribute water to crop
 * When**: Started around 4000~3000BC in both Mesopotamia and Egypt