Ubaid period
The earliest sedentary culture in Saudi Arabia dates back to the Ubaid period, upon discovering various pottery sherds at Dosariyah. Initial analysis of the discovery concluded that the eastern province of Saudi Arabia was the homeland of the earliest settlers of Mesopotamia, and by extension, the likely origin of the Sumerians. However, experts such as Joan Oates had the opportunity to see the Ubaid period sherds in eastern Arabia and consequently conclude that the sherds date to the last two phases of the Ubaid period (period three and four), while a handful of examples could be classified roughly as either Ubaid 3 or Ubaid 2. Thus the idea that colonists from Saudi Arabia had emigrated to southern Mesopotamia and founded the region's first sedentary culture was abandoned.