Mesopotamia was located between the Tigris and Euphrates Rivers in modern-day Iraq. This civilization began around 3500 BC and lasted for over 3000 years, during which several empires and city-states rose and fell. Some influential cities included Ur, Uruk, Akkad, Babylon, and Nineveh. The Mesopotamians were among the first to develop irrigation for agriculture, writing, law codes, and architectural techniques like the arch and vault. Power was held by rulers of the city-states and later empires, including the Sumerians, Akkadians, Babylonians, and Assyrians. The Mesopotamian civilization marked many important advances and innovations