The Early Dynastic Period is an archaeological culture in Mesopotamia that is generally dated to c. 2900 – c. 2350 BC and was preceded by the Uruk and Jemdet Nasr periods. It saw the development of writing and the formation of the first cities and states. The ED itself was characterized by the existence of multiple city-states: small states with a relatively simple structure that developed and solidified over time. This development ultimately led, directly after this period, to broad Mesopotamian unification under the rule of Sargon, the first monarch of the Akkadian Empire. Despite their political fragmentation, the ED city-states shared a relatively homogeneous material culture. Sumerian cities such as Uruk, Ur, Lagash, Umma, and Nippur located in Lower Mesopotamia were very powerful and influential. To the north and west stretched states centered on cities such as Kish, Mari, Nagar, and Ebla.