Which Sumerian city was very powerful and influential during the Early Dynastic period and once a coastal city?
Early Dynastic Period (Mesopotamia):  Sumerian cities like Uruk, Ur, Lagash, Umma and Nippur, located in Lower Mesopotamia, were very powerful and influential. Ur:  Although Ur was once a coastal city near the mouth of the Euphrates on the Persian Gulf, the coastline has shifted and the city is now well inland, on the south bank of the Euphrates, 16 kilometres (9.9 mi) from Nasiriyah in modern-day Iraq.
Ur