A chronological phase in southern Mesopotamia between c 2900-2330 BC, ending with the founding of the Dynasty of Akkad. It was also known as the Pre-Sargonid period. The Sumerian city-states flourished under their separate dynastic rulers - Ur, Umma, Kish, and Lagash. The period is 3100-2450 BC on what is called the "high chronology" (the other being the "medium chronology"). The term itself is derived from the Sumerian 'king list' which implies that Sumer was ruled by kings at this stage although archaeological evidence for the existence of kingship is meager before the middle of the period. Traditionally it is divided by archaeologists into three subdivisions - ED I II and III - each of approximately 200 years duration. The Royal Tombs of Ur belong the ED III period. The Early Dynastic phase shows clear continuity from the preceding Jemdet Nasr and represents a period of rapid political cultural and artistic development. Within the period the pictographic writing of the earlier period developed into the standardized cuneiform script. This period represents the earliest conjunction of archaeological and written evidence for the history of southern Mesopotamia.