 Juris Zarins believes the Sumerians lived along the coast of Eastern Arabia, today's Persian Gulf region, before it was flooded at the end of the Ice Age.Sumerian civilization took form in the Uruk period (4th millennium BC), continuing into the Jemdet Nasr and Early Dynastic periods.During the 3rd millennium BC, a close cultural symbiosis developed between the Sumerians, who spoke a language isolate, and Akkadians, which gave rise to widespread bilingualism.